This Snail Built Its Own Metal Armor (Thanks, Volcanoes)

In this Volcano Minisode, Katy introduces one of the most extreme animals on Earth: the scaly-foot gastropod, a deep-sea snail that literally builds metal armor from volcanic hydrothermal vents. Found over a mile below the ocean’s surface, this snail survives crushing pressure, toxic heat, and total darkness—all thanks to a symbiotic relationship with bacteria and its one-of-a-kind iron shell.

🧪 How does a snail use volcanic metals to build armor?
 🌋 What makes hydrothermal vents so hostile—and so essential to life?
 🧫 And who’s really in charge here… the snail or the bacteria living inside it?

This episode is a deep dive into extreme evolution, powered by volcanoes and gut flora. It’s weird, real, and one of the coolest stories in nature.

👉 This is episode 4 of 6 in our Volcano Minisodes series—bite-sized, bizarre, and bursting with molten-hot science facts.

🎧 Listen now to meet Earth’s most metal mollusk.

Transcript

Laura: [00:00:00] Hello and welcome to Wildly Curious, a podcast that tells you everything you need to know about nature, and probably more than you wanted to know. I'm Laura.

Katy: And I'm Katy, and today we're talking about volcanoes and the surprising things that they've made buried and accidentally made cooler so I had, buried, protected the, the pyramid, and then I talked about obsidian.

Laura: Made and made cooler.

Katy: Yeah, made and made cooler. I think this one is another made and made

Laura: Okay.

Katy: So this is about a snail that wears armor.

Laura: Ooh.

Katy: Okay. All right.

Laura: but cool.

Katy: Yes. So let's start this one off with a question. What would you say is the toughest animal on earth?

Laura: Well, I

Katy: Knowing that I just told you the snail wears wears armor.

Laura: a snail, toughest animal on earth. I probably would've said is like, , oh geez, they a Pima. Since we were talking about that with , those fish scales that are like basically bulletproof

Katy: So it's that people, crocodiles, that kind of stuff. It could very much well be this,

Laura: know.

Katy: [00:01:00] yeah, it very well could be this snail though, so this scaly foot Gastropod, also known by its very scientific name, Christ Lium.

Laura: Hey, that's pretty good.

Katy: Thank you. I went into it fairly really confident. And so this snail was discovered in 2001. Hanging out at the bottom of the Indian Ocean about 2,400 meters deep, which is well over a mile and a half deep. Living in hydrothermal vents. Dear this volcano and these vents, they're deep sea hot springs, except instead of relaxing spas, it's scolding toxic chemicals.

Just zero

Laura: Melt your face off. Yeah, yeah,

Katy: Yes. Uh, melt your body off. Yeah. So what does this scaly foot gastropod say? Perfect place to live?

Laura: think we talked about hydrothermal vent in our extreme of files episode.

Katy: We did. Yeah, we did. So depending on the [00:02:00] hydrothermal vent and where you are, these vents pump out water that can reach temperatures of 350 degrees Celsius over a 660 degrees Fahrenheit, full of dissolved metals, sulfur, and all kinds of stuff that would just destroy the average life form.

Except for like we talked about in that episode, there's nothing average that lives near these things 'cause they, they can't. So that's where this snail didn't just tolerate this extreme environment. It has learned to thrive in it. It's a developed a one of a kind adaptation that makes one of the most fascinating.

I didn't know that this thing even existed. So because its entire body, its shell, its. Foot, which is the bottom part that you guys see. This, comes along the snail. Even this, the scales on this little squishy part are built for this whole thing. All right, so the snail shell has been made of metal.

All right?

Laura: so normally, I guess, [00:03:00] hold on real quick. Normal snail shells are secreted and it's calcium carbonate or something like that.

Katy: something like that. It's some sort of calcium. Yeah. So this one, because of the environment, it's the shell of it is iron sulfide, which is pulled from the vents around it and pulled into its body. So this is the only animal on earth that we know of that incorporates metal into its skeleton.

Laura: freaking cool.

Katy: Right? So here's how, how, how it works.

It has, the shell has three distinct layers. Layer one is the outermost layer and it's made of the iron sulfide. Like I said. With compounds like Pyrrhotite, and anite, which gives it a dull metallic shimmer. Think of a medieval night kind of looking

Laura: I already am. I already am thinking about the snail.

Katy: right? There we go.

Layer two, then. Layer two then is a layer of protein, and then layer three is [00:04:00] the innermost layer of the A granite.

It's a type of calcium carbonate, like we said, that's common in the mollusk shells.

So this armored snail, I guess this one is another one, like the pyramids where it's protection because the snail has.

Grown to evolve there. Not a whole lot can. This little snail has only been found. Now granted, it's not like we go around like exploring these hydro thermic vents all the time, but they have found and only three hydrothermal vent fields in the Indian ocean.

That's it. And because of that, they've classified it as critically endangered. Again, I'm not knocking this, the snail here. It's like, how sure are we that they're not like,

Laura: bent. Yeah,

Katy: yeah. Like how well have we really explored

Laura: Yeah,

Katy: Yeah. So, so anyway,

Laura: it's like a little iron man's nail.

Katy: no. Right. So it doesn't just live near the volcanoes or the hydro thermic vent. It literally depends on it. So the vents, don't just provide warmth and everything for things down there instead of sunlight because it's so, so deep.

Life [00:05:00] here runs in Chemosynthesis, which we've talked about before. It's a process where bacteria feed on the chemicals coming from the earth deep within.

Laura: Rather than the whole sunlight food chain thing.

Katy: Yep. And so the snail, it's a walking partnership, so it houses a symbiotic bacteria and a special organ in its body, like an internal, , I dunno, bacteria garden, so the SNA doesn't have to hunt, doesn't have to scavenge. It's like a quiet, like chemical

Laura: is bananas. That's like those, didn't we find like there were squid or something that have the glowing bacteria inside of them or something.

Katy: I think so. Yeah, I think

Laura: Where you're like, you are a house for bacteria. Like we all, we've come to realize, we all are really, but, but this is extra.

Katy: Yes. So the snail, it lives in total darkness at crushing temperatures with boiling chemical water around it. And then it powers itself from farming bacteria, which is inside of its own body.

Laura: the, food for thought. What if, you know how, we've talked about bacteria and gut flora before and you know how who's [00:06:00] really in charge of this body? Really? You know what I mean? What if the bacteria were like, how would we survive down here? And they've basically forced this evolution of this

Katy: Yeah. Right.

Laura: to be like, put armor on it.

Like, you know

Katy: build it big. Ah, yeah.

Laura: Like,

Katy: We need, we need eyes now. We need like, and it just over generations of bacteria

Laura: start sucking in metal, suck in metal and ex, you know, push it out 'cause

Katy: and it's all these little blacksmiths in there. Like, like go work away. Work away. So, yeah, , it's a, it's a snail, I didn't know, first of all, I was like reading down through it and there's so much more, just if you just google volcanic snail, I literally have scratched the armor surface of it.

Laura: soon as you see a TED line like metal snail, you'll be like, Hmm. Because it sounds like a Pokemon, there is a magma. Slug, right? There's like slug MA or something, some magma,

Katy: Oh, I don't know. I don't

Laura: but I don't bet it's not. I bet it's not off of that. It's not a [00:07:00] metallic one. There should be Pokemon creators.

Here's your new one.

Katy: Come on guys.

Laura: is easy.

Katy: yeah,

Laura: this one to you.

Katy: Yeah, right. You heard it Here folks. Next Pokemon comment from the Wildly Curious Podcast. So anyway, so yeah, volcanic snail. So I thought that was, that one was pretty awesome. 'cause again, I'd never heard of it. And then I was researching it more.

I was oh wow, the metal with this, the shell and everything. I was like, that's really awesome. And then reading more about like how it depends on the vents because of the gut and it, how that relationship works. And that's literally how it survives of just producing it its own

Laura: wouldn't exist without the volcanic vents. So I'll go back down to the volcano too.

Katy: Yep. Yeah, so anyway. Really cool. Alright guys, well make sure you subscribe to us on our YouTube channel, uh, and Facebook. And do you see auto right

Laura: I know I saw his little face. He's very engaged.

Katy: Alright, so make sure you go subscribe to us on YouTube. Help us out [00:08:00] there. We have all the shorts, and then these long videos that you can see. Um, and then tune in next week for what, which will be the last episode of these mini episodes. And then we'll be kicking off season 12 from there.

Laura: Cool. All right. Talk to y'all next week.