Was Atlantis a real city? If not, why have so many people gone looking for it? In part two of our series on modern myths and legends, we’re searching for lost cities.

We’ll trace the origins of El Dorado, and head to the ruins of an actual lost city in Egypt. We'll find out how mangrove trees could help prevent cities from being lost to climate change, and Sanden and Marc are back with another edition of Hoax Hunters. Plus, a Moment of Um about how tattoos stay put.

Educators - Lesson Plan for Brains On! - Lost Cities: Making Sense of Myths, pt. 2 (Right Click to Download)

Audio Transcript

Download transcript (PDF)

MOLLY BLOOM: A quick note before we start the show-- in this series, we're taking a look at myths from modern-day legends to stories that are thousands of years old. Some of them might seem a bit scary, but we're talking about them because we want to understand the important role they play in our lives and dig into the history and facts behind them. And, of course, there's all the usual Brains On fun too. OK, on with the show.

BOY: You're listening to Brains On, where we are serious about being curious.

GIRL: Brains On is supported in part by a grant from the National Science Foundation.

ELLIOT: A long, long time ago a tribe of people lived in South America in the Andes mountains near a sacred lake. They had a special tradition. Whenever a new leader came into power--

MAN AND WOMAN: Our new leader--

WOMAN: Quick, ready the raft.

ELLIOT: They covered the new leader in gold dust. They gathered heaps of gold and emeralds. Then the leader and the treasure floated out to the middle of the lake on a raft.

MAN: Off you go.

WOMAN: Ooh, did you see that gold? Oh my God.

MAN: That is an amazing amount of gold.

WOMAN: Gosh, those huge pile.

ELLIOT: Once the raft reached the middle of the lake, the leader signaled for silence. Then the leader threw the gold and emeralds into the water as an offering to a god who live at the bottom of a lake. Once the raft came back toward land, the tribe cheered on their new leader.

MAN: The god at the bottom of the lake will be so pleased.

ELLIOT: When Spanish explorers came to South America and heard about this tradition, their eyes lit up.

SPANISH EXPLORER 1: Have you heard how this tribe celebrates a leader? All that gold.

SPANISH EXPLORER 2: El Dorado.

ELLIOT: Dorado means gold in Spanish. And over time, the legend morphed into being about a city of gold left behind by these tribes and hidden in the forest. And many, many people look for this stockpile of treasure.

SPANISH EXPLORER 1: It's got to be here somewhere.

ELLIOT: Explorers did find gold and gems at the bottom of the lake in Colombia, Lake Guatavita. But the mythical city of El Dorado has never appeared. Maybe the riches are still waiting somewhere.

[MUSIC PLAYING]

MOLLY BLOOM: This is Brains On from American Public Media. I'm Molly Bloom, and my cohost today is Elliot from Bemidji, Minnesota. Hi, Elliott.

ELLIOT: Hi.

MOLLY BLOOM: This episode is part two of a four-part series on myths and legends.

ELLIOT: In the last episode, we scanned the horizons for mythical creatures on land. Check it out if you haven't already.

MOLLY BLOOM: In this episode, we're finding our way toward lost worlds--

ELLIOT: Cities mysteriously hidden in the jungle--

MOLLY BLOOM: Civilizations wiped out in giant floods--

ELLIOT: Islands that sunk to the bottom of the sea.

[MUSIC PLAYING]

MAN: (SINGING) From the depths of time up through today, myths and legends whine their way into culture and into lore. But is there truth? Well, let's explore.

Scanning the clues of history for creatures on land and in the sea, lost worlds hidden under your toes. Hey, over there. Is that a UFO?

Armed with knowledge and with proof. Help us to uncover what is real and what's a spoof. Myths and legends, we'll discover.

MOLLY BLOOM: So Elliot, have you ever heard a story about a lost world?

ELLIOT: Oh, I think about Pompeii.

MOLLY BLOOM: Yeah, so Pompeii was a city in Italy that existed until the volcano Mount Vesuvius erupted and wiped it out.

ELLIOT: It's like gone.

MOLLY BLOOM: Yeah, the ash covered the city, and they had to excavate it. They had to dig it up to find the city. And so the city's kind of been preserved in ash. It's very, very cool.

So Elliot, if you were going to look for a lost city, where would you look?

ELLIOT: I would look near water because most lost cities have been like flooded by floods.

MOLLY BLOOM: So they were there, and then they got covered by water?

ELLIOT: Mm-hmm.

MOLLY BLOOM: That is a great idea, Elliot. There's one mythical island called Atlantis that has a really famous story of being flooded. We asked mythology expert Sara Burdorff to join us again to talk about that story and others.

SARA BURDORFF: Hi, Elliot.

ELLIOT: Hey. Can you tell us the story of Atlantis?

SARA BURDORFF: I would love to tell you the story of Atlantis. A long, long time ago, Poseidon, who was the Greek God of the sea, was given an island, a huge island, and he fell in love with a lady who lived on the island. And they had 10 sons.

And he made those sons the kings of this giant island. It was a beautiful place to live, and the weather was perfect. And they had all the food they needed.

And when they dug in the ground, they found so much silver and gold and precious metal that they could use it for their buildings. That's how much they had. To make sure that they stayed peaceful and that they stayed as happy as they were when the island started, Poseidon gave them laws and rules to follow to be kind to each other and to take care of each other.

But the longer they lived on the island, they started to forget why those rules were important and forgot so much about what Poseidon had wanted them to remember that Poseidon's brother, Zeus, who was the king of all of the Greek gods, he decided that he needed to teach them a lesson. And so in one day and one night, he flooded Atlantis. He sent earthquakes and giant tidal waves, and he washed the city away.

And all the buildings crumbled into the sea, and the island disappeared. And Atlantis didn't exist anymore.

MOLLY BLOOM: Wow.

ELLIOT: Holy cow.

SARA BURDORFF: [CHUCKLES] It's funny that you would say holy cow, Elliot, because one of the symbols for Poseidon is actually a bull. And that was one of their sacred animals on Atlantis. So they actually had holy cows.

[COW MOOING]

MOLLY BLOOM: [CHUCKLES]

SARA BURDORFF: [CHUCKLES]

MOLLY BLOOM: That's awesome. Where do stories about floods or underwater worlds come from?

SARA BURDORFF: Yeah, there are a couple of different theories about where they might come from. People would find sometimes just from the way that the world was formed, they would find an imprint or a fossil of a seashell on top of a mountain. And they would think like, how did that get there? So that's one possibility.

Another possibility comes from an original story based on an original event. So if a local river flooded, people remembered it for a long time. And then when those people migrated out of that area, they took that story and those memories of that very big event with them.

MOLLY BLOOM: How did these stories help the people who told them?

SARA BURDORFF: Telling a story about how something came to be can help us make a little bit more sense out of it. Another thing that stories do, they help us explore possibilities. So they are those kind of what if experiences where-- imagine if you had an island that the gods were taking care of but then the people got greedy and selfish, what would happen, or what could happen? And those what ifs, those wonderings, they're used to teach lessons.

MOLLY BLOOM: So myths and legends might have helped people think about possible situations like giant rainstorms or flooded rivers. And maybe those stories also taught people ways of handling different situations.

SARA BURDORFF: Yeah, exactly. So it can also help shape a sense of community because if people all tell a story a similar way, that's their story, and that's their little piece of the universe.

MOLLY BLOOM: Thank you so much for joining us.

ELLIOT: Thank you.

SARA BURDORFF: Thank you so much for having me, Elliot and Molly.

MAN: (SINGING) Brains On-- [CLEARS THROAT]

MOLLY BLOOM: El Dorado and Atlantis are two mythical lost cities we've never found. Sometimes archeologists do find cities that seemed lost. Brains On producer Menaka Wilhelm has a story of one of those cities in Egypt.

MENAKA WILHELM: Around 2,500 years ago, this city was a big bustling place. It was the gateway to Egypt right where the Nile River meets the Mediterranean Sea. There is a busy harbor and lots of canals. It was bigger than Pompeii, that famous city in Italy.

People here lived in mudbrick houses, and they built big temples made of stone. And visitors came here from all around the Mediterranean. They came to trade goods and also for big festivals celebrating the Egyptian gods.

Then one day, it disappeared. So at first, researchers learned about this place in ancient texts. People wrote about this place. And that's how we learned its name.

AURELIA MASSON-BERGHOFF: Thonis-Heracleion.

MENAKA WILHELM: Aurélia Masson-Berghoff is an Egyptologist who has studied Egyptian cities like Thonis-Heracleion. She and other researchers knew it existed because they found all kinds of records in nearby places. They sell taxes. People had paid for bringing goods into Thonis-Heracleion and notes about people who visited Thonis-Heracleion.

But where was Thonis-Heracleion itself? The record stopped about 1,500 years into the city's history. And no one could find any part of the city anywhere in Egypt. Sometimes ancient cities in Egypt get buried in sand. And archeologists figured maybe that's what happened here.

AURELIA MASSON-BERGHOFF: Nobody suspected that the city was submerged under the water.

MENAKA WILHELM: The very first clue about finding the city came in the 1930s when a Royal Air Force pilot was flying over the Mediterranean Sea north of Egypt.

MAN: There's something down there in the water.

MENAKA WILHELM: That seemed really interesting to an archeologist named Franck Goddio. But he didn't know exactly where to look in the sea at first. He and his crew used sound waves and other measurements to search underwater.

It took years. But eventually, they found something. Now, I hope you've got your scuba suit and swim fins ready because we're going about 30 feet underwater to the remains of the lost city of Thonis-Heracleion.

I asked a diver named Eric Wartenweiler Smith to show us around. He helped uncover Thonis-Heracleion with Franck Goddio's team. Let's dive in.

[SPLASH]

ERIC WARTENWEILER SMITH: Now, one thing, when we get to the bottom, we take our fins off. We're wearing a lot of heavy weights and equipment. So you can kind of walk around on the bottom.

MENAKA WILHELM: So we're breathing air from oxygen tanks and wearing wet suits to stay warm. The water is a bit murky, but we can look around through our scuba masks.

ERIC WARTENWEILER SMITH: There's plenty of rocks, and there's fish swimming around. And there's piles of sand and debris that you and your team have pulled out.

MENAKA WILHELM: When Eric dove here, he and his team used lots of different tools to dig up items from Thonis-Heracleion that were buried in the sand. One tool is almost like an underwater vacuum.

ERIC WARTENWEILER SMITH: And it sucks up the material, the sand, and the mud, and it blows it a few feet away.

MENAKA WILHELM: They also found some things without any digging at all.

ERIC WARTENWEILER SMITH: Even though the city has been on the bottom of the sea for thousands of years, there's plenty of times where we would just be walking along and see a rock. And then underneath the rock was a bronze bowl with images on it. And it's just there.

MENAKA WILHELM: They found giant stone statues and the walls of a temple. They've also found big ceramic jugs, metal lamps, and gold jewelry, and coins. Each item tells us more about what Thonis-Heracleion was like as a city and how it changed over time.

And the team has started to piece together why Thonis-Heracleion ended up under the sea. It seems like the city sank when an earthquake hit. The earthquake shaking created giant waves or a tsunami.

And when those giant waves flooded the city's sand and clay soil, it pushed the city under the sea. For thousands of years, the city was lost. But in a way, being lost for all that time has made it easier for us to learn about Thonis-Heracleion now.

In other Egyptian cities, historical items got damaged or reused and made into other things. It can be hard for archeologists to find statues or coins or ceramics in their original form.

AURELIA MASSON-BERGHOFF: But because Thonis-Heracleion was sunken under the sea, a lot of these objects are perfectly preserved.

MENAKA WILHELM: And there are hundreds of years of history to find here. Franck Goddio's team is still learning more about the site.

AURELIA MASSON-BERGHOFF: Despite all the things they have discovered, it's said that only 5% of the cities has been explored.

MENAKA WILHELM: So even though archeologists have found amazing things at Thonis-Heracleion, so far, it turns out there's even more lost city to find in the future.

ROBOT: Brains, brains, Brains On.

MOLLY BLOOM: We've got something to uncover too. Shh.

GIRL: Mystery sound.

MOLLY BLOOM: Are you ready for the mystery sound, Elliot?

ELLIOT: Oh, I'm ready.

MOLLY BLOOM: All right, here it is.

[MYSTERY SOUND]

What is your guess?

ELLIOT: I hear some metal, like buckets banging against each other.

MOLLY BLOOM: Excellent guess. So you definitely heard metal. Well, we're going to give you another chance to guess in just a bit.

[MUSIC PLAYING]

Have you got questions for Brains On? Maybe you've drawn a super cool mythical creature or heard a silly strange sound?

ELLIOT: Hit us up at brainson.org/contact.

MOLLY BLOOM: We love checking out everything you sent in. Brainson.org/contact is the place to send questions, drawings, and mystery sounds. That's how we got this question.

LOGAN: Hi, my name's Logan from Queen Creek, Arizona. And my question is, how does a permanent tattoo stay forever?

MOLLY BLOOM: We'll get to the bottom of that at the end of the show.

ELLIOT: So keep listening.

You're listening to Brains On from American Public Media. I'm Elliot.

MOLLY BLOOM: I'm Molly.

MARC SANCHEZ: I'm Marc.

SANDEN TOTTEN: And I'm Sanden.

MOLLY BLOOM: Oh, hi, guys. You're back.

MARC SANCHEZ: Yeah, for another edition of Hoax--

SANDEN TOTTEN: Oh, whoa, whoa, wait, wait, wait. Let's count it down. Ready? 3, 2, 1.

MARC AND SANDEN: (SINGING) We like myths, but we hate getting tricked, yeah. We like myths, but we hate getting tricked, yeah. We like myths, but we hate getting tricked.

MARC SANCHEZ: We hate getting tricked. No, we don't like it.

SANDEN TOTTEN: Yeah.

MARC SANCHEZ: [CHUCKLES] Yeah.

SANDEN TOTTEN: We're uncovering hoaxes throughout history.

MARC SANCHEZ: First off, a hoax is when someone tricks you into believing something that's not true.

SANDEN TOTTEN: Like that time you tricked me into thinking there was a two-for-one sale on sacks of sugar at the sugar store?

MARC SANCHEZ: [CHUCKLES] I know. I've never seen anyone run so fast. It was awesome.

SANDEN TOTTEN: Ugh. Anyway, today we're looking at a case from 1885 when the local newspaper in Moberly, Missouri, published a sensational story.

MARC SANCHEZ: The report said that miners had accidentally discovered an entire city hidden over 300 feet below ground. They said they found roads and walls and tools and even art.

SANDEN TOTTEN: And most amazing of all, a skeleton three times the size of a normal person, a giant.

MARC SANCHEZ: Have there once really been a secret society of giants living below the city of Moberly?

MARC AND SANDEN: Nah.

SANDEN TOTTEN: On April 11th, the newspaper's editor fessed up. He said the story is an April hoax, not a word of truth in it.

MARC SANCHEZ: So there you have it. Hoax hunted.

SANDEN TOTTEN: All right. Let this be a lesson to all of us. Always check your facts and sources, especially if a story seems a bit fishy or gianty.

MARC SANCHEZ: Yeah. We'll catch you next time on 3, 2, 1, Hoax Hunters. Yeah.

MOLLY BLOOM: Let's get back to that mystery sound. Here it is again.

[MYSTERY SOUND]

OK, so last time you were very sure you heard metal. Do you have any other thoughts?

ELLIOT: Ooh, cars. Like they're rubbing cars against each other.

MOLLY BLOOM: Well, are you ready for the answer?

ELLIOT: Yep.

MOLLY BLOOM: The sound you just heard was a sewer cover being removed. So sewer covers are those big metal circles you sometimes see in a road. They usually lead to sewers or pipes.

But if you found the rights to recover in Manchester, England, it would lead you to an abandoned underground neighborhood.

It's called the Victoria Arches. And it's a network of tunnels, shops, and cellars constructed over 100 years ago. They built these tunnels underground to connect with the river that runs through the city in a canal way below street level.

The idea was you could hop off a riverboat and head straight into a tunnel filled with shops. But eventually, after a lot of flooding and a lot of pollution the city decided to close off the Victoria Arches. And now, many people don't realize this underground part of the city ever existed.

Similar things have happened all over the world, like in downtown Seattle, where there's a whole neighborhood hidden underground. In the late 1800s, this part of the city was at street level. But when a fire destroyed 31 blocks, the city decided to build on top of the old neighborhood, creating a lost world right beneath people's feet.

ELLIOT: Humongou-- holy cow.

MAN: Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On.

MOLLY BLOOM: So far, we've talked about different places that were lost in the past. But did you ever think about losing cities in the future? Our Brains On reporter Ruby Guthrie is here to talk all about it. At least, she's supposed to be here.

[DOOR CREAKING]

RUBY GUTHRIE: [EXHALES] Molly, ugh, sorry, I'm late. I just ran over here from the airport. Have you ever tried running in rain boots? I don't recommend it.

MOLLY BLOOM: Well, that's OK. Why are you wearing rain boots?

RUBY GUTHRIE: Well, I just got back from Miami, Florida, where I was learning about flooding. Miami's always had floods, especially after hurricanes and heavy rains. But now sometimes some neighborhoods near the shore are flooding, even on the sunny days.

MOLLY BLOOM: Oh, all right. I've heard about this. It's not just Miami. Cities and towns on coasts around the world are flooding more and more often.

Scientists say it's all because of sea level rise.

RUBY GUTHRIE: Exactly. Sea level rise is another effect of climate change, something you've talked about before on the show. But just to remind everyone, I'm going to do a 30-second recap. Got the timer ready?

MOLLY BLOOM: Yep. Ready, set, go.

RUBY GUTHRIE: OK. The Earth is getting warmer because of this gas called carbon dioxide, aka CO2. Humans exhale CO2 [EXHALES] just like that. But you also release a lot more of it when we burn stuff called fossil fuels.

Fossil fuels are things like gas and coal. We burn them to heat our homes and power our cars and lots of other reasons. Now when CO2 goes up in the air, it actually traps heat in our atmosphere. So over time, as we release more and more CO2, our planet gets warmer and warmer.

MOLLY BLOOM: And time. Nice job, Ruby.

RUBY GUTHRIE: Thanks. So those are just the basics. As the Earth heats up, so does the ocean.

And when things heat up they expand, which makes sea levels rise. Plus, all that extra heat is melting the glaciers, which also raises sea levels. Some people worry if this continues. Whole cities just like Miami could end up underwater.

MOLLY BLOOM: Yikes, like Atlantis.

RUBY GUTHRIE: Right. But I talked to a scientist who says this doesn't have to be our destiny.

TIFFANY TROXLER: What's interesting is that climate change, which causes sea level rise, is a human-caused issue.

RUBY GUTHRIE: That's Tiffany Troxler from Florida International University. She's the director of science at the Sea Level Solutions Center. She studies how sea level rise affects our environment and our lives.

TIFFANY TROXLER: There are things that we can do as humans to both mitigate the extent of things like sea level rise, as well as reduce or adapt to the impacts of sea level rise, which would help to make us not turn into Atlantis. [CHUCKLES]

RUBY GUTHRIE: Tiffany says there are two types of sea level solutions.

TIFFANY TROXLER: We can do mitigation, which is to reduce the amount of greenhouse gases going into the atmosphere.

MOLLY BLOOM: Like riding your bike instead of driving a car that burns fossil fuels.

RUBY GUTHRIE: Exactly.

TIFFANY TROXLER: Then there's adaptation. These are strategies that are used to reduce the impacts of sea level rise.

RUBY GUTHRIE: This includes things like raising up buildings in flooded areas or moving away from the coastline. Some solutions use mitigation and adaptation. One of my personal faves is the--

MOLLY BLOOM: Massive super cyborg that sucks up the seawater and also eats carbon?

RUBY GUTHRIE: That sounds awesome, but I was actually thinking of something in nature that's existed for thousands of years. They're called--

MOLLY BLOOM: Mermaids. Oh, yes, mermaids can solve everything.

RUBY GUTHRIE: Not quite. I'm talking about mangroves.

MOLLY BLOOM: Man, what now?

RUBY GUTHRIE: Mangroves. They're a type of tree that grows on coastlines, but they're not just any tree. They're flood-fighting superheroes. I actually brought one back for you. Bring it in.

MOLLY BLOOM: You put an entire tree in your suitcase?

RUBY GUTHRIE: Oh, yeah. I'm a really good packer. Anyways, here's your souvenir. [GRUNTING]

MOLLY BLOOM: Ooh. Thanks.

RUBY GUTHRIE: This is Manuel, the mangrove. Say hi, Manuel.

MOLLY BLOOM: That's OK, Ruby. Most trees don't talk.

RUBY GUTHRIE: Oh, but Manuel isn't like most trees. He's super resilient, which means he can survive really difficult conditions.

MOLLY BLOOM: OK, so looking from the top down, you got your standard green leaves, grayish brown trunk, but holy moly, look at those roots. They're all knottled and tangled and overlapping in every direction.

RUBY GUTHRIE: Bananas, right? Mangroves grow in places with very wet soil. Wet soil doesn't have enough oxygen for most plants. But mangroves survive because they get extra oxygen through tiny cell size pores on the surface of their bark and on those wild aboveground roots.

MOLLY BLOOM: That's amazing.

RUBY GUTHRIE: That's not even the best part. Mangroves also grow in places that get flooded by super salty ocean water. Saltwater would usually dry up your everyday run-of-the-mill plant, but not a mangrove. Oh, no.

The tree either filters out the salt from the root or pushes out the salt crystals through the leaves. Manuel you're just full of superpowers, huh? [SIGHS] He's just a humble guy. What can I say?

MOLLY BLOOM: That's cool and all. But how does it help a sea level rise?

RUBY GUTHRIE: So mangroves, like all plants, take carbon dioxide from the air and use it to help their roots, branches, and leaves grow. Eventually, the leaves and branches fall off and are buried deep into the soil, where the carbon is locked away. That means less carbon in the atmosphere and less warming.

MOLLY BLOOM: And less sea level rise.

RUBY GUTHRIE: Right. Mangroves are also a great first line of defense against floods and tropical storms. Their tangled roots slow down the waves and prevent the soil from washing away. But it doesn't end there.

Mangroves can actually build up their soils vertically to prevent further erosion. This keeps the coastline strong, preventing the waves from creeping past the beach and flooding neighborhoods

MOLLY BLOOM: Wow. OK, that is a super tree.

RUBY GUTHRIE: Right? But as amazing as mangroves are, they're just one of many solutions we're going to need to help fight climate change.

MOLLY BLOOM: Well, thanks for stopping by Ruby and thanks for bringing Manuel.

RUBY GUTHRIE: Of course. Now, I'm going to make like a tree and leave. [CHUCKLES] Get it?

MANUEL: That pun was bad.

MOLLY BLOOM: Manuel?

RUBY GUTHRIE: Manuel, I knew you'd come around. But hey, you taught me that one.

MANUEL: Yes. I regret that now.

RUBY GUTHRIE: Manuel--

[MUSIC PLAYING]

ELLIOT: People all over the world have legends about lost places.

MOLLY BLOOM: These legends tell us that cities and lands have shifted in the past.

ELLIOT: Sometimes in places like Seattle, new [INAUDIBLE] cities got built right on top of the other ones.

MOLLY BLOOM: Farther back in history, cities did get swept underwater, like Thonis-Heracleion in Egypt.

ELLIOT: But if you hear about a lost city and it seems made-up, maybe check those facts.

MOLLY BLOOM: Sea level rise is a threat to cities on the coast today. But there are many ways scientists are working to mitigate and adapt to this change. That's it for this episode of Brains On.

ELLIOT: Brains On is made by Menaka Wilhelm, Sanden Totten, Marc Sanchez, and Molly Bloom.

MOLLY BLOOM: Elyssa Dudley, Ruby Guthrie, Rosie duPont, and Tracy Mumford made this mythical series a reality. We had engineering help from Veronica Rodriguez, John [INAUDIBLE], Valentino Rivera, and Eric Romani. We also had production help from Kristina Lopez. Special thanks to Will [INAUDIBLE], Hannah Yang, [? Eric ?] [INAUDIBLE], and [INAUDIBLE]

[MUSIC PLAYING]

ELLIOT: Before we go, it's time for our Moment of Um.

[MOMENT OF UM]

BOY: How does a permanent tattoo stay forever?

ROOPAL KUNDU: I am Roopal Kundu, and I am a dermatologist at Northwestern Medicine in Chicago, Illinois. A dermatologist is a doctor or a physician who takes care of people's issues with their skin, hair, and nails. So the tattoo is injected by a needle, and the needle just holds that ink. And it penetrates through the skin.

The skin has two main layers. The top layer is called the epidermis. That's what we see on the outside. And that layer of the skin actually is constantly shedding. That's the skin cells that are shedding.

Every month, you have a new layer of epidermis that's generated. But now, that needle with the ink in it is going into the next layer of skin called the dermis. And that layer doesn't shed. It stays put.

So tattoos are basically small tiny little injuries to the skin. And what happens any time you have a wound is that cells, immune cells, come and try to heal that wound. And in this case, there's a certain type of cell called macrophages.

And those cells basically try to eat up the tattoo ink. And because the tattoo ink is so big, they're able to clamp onto it, but they really can't chew it all up. And so that tattoo ink gets stuck in those macrophages, and they just hang out there in that layer called the dermis. And then you have a tattoo.

One of the ways laser technology works when people try to remove their tattoos-- the laser is processing lots of heat, lots of energy. And that energy essentially heats up the tattoo ink, expands it, but then kind of shatters it. And it breaks up into tiny little pieces.

And then those pieces are small enough for the macrophages to chew up and remove from the dermis, the skin, and then you get the lightening over time. It's just that it takes lots and lots of treatments to do that and lots of time.

[MOMENT OF UM]

MOLLY BLOOM: These names are permanently in my heart. It's time for the Brains Honor Roll. These are the amazing listeners who send us their questions, ideas, drawings, and high fives.

[MUSIC PLAYING]

[LISTING HONOR ROLL]

ROBOT: Brains Honor Roll Bye. Bye.

MOLLY BLOOM: We'll be back soon with more answers to your questions. Thanks for listening.

Transcription services provided by 3Play Media.