Sableye hides in caves and eats rocks. It sounds obscure, sure, but it does Sableye a lot of good. In our previous entry on Sableye, for example, we discussed how using the gems in its eyes gives Sableye improved vision, useful for dark caves. But we’ve gotten a bunch of requests recently that want to know the how: How do the rocks Sableye eats become part of its body?
When we eat something, parts of the food naturally becomes part of our bodies: that’s why we eat. The proteins, vitamins, sugars, and more from food are broken down, absorbed, and then added to our bodies. However, as you can imagine, rocks aren’t easily digestible. They can’t be chewed up and broken down, and therefore it’s components can’t be absorbed into our bodies.
However, eating rocks is more common than you might think: but it’s never for nutrition. Birds, crocodiles, sea lions, ostriches, frogs, and axolotls are all known to swallow rocks. There’s also evidence that several dinosaurs did this. Once a rock is swallowed, it becomes known as a gastrolith. Ostriches, sometimes, will swallow rocks up to 10 centimeters in diameter. These animals swallow these rocks to help them in digestion. All of these animals either don’t have teeth, have limited teeth, or have teeth that aren’t good for chewing. These animals can’t chew their food, so they swallow rocks so the food can be ground up and “chewed” by the rocks in their stomach. Just like chewing does for us, the rocks grind up the food to help these animals get the most vitamins, proteins, and nutrition out of the food that it eats.
But, like I mentioned, these rocks aren’t for nutrition. These animals can’t digest the rocks they eat, and no part of the rock is digested, absorbed, or added to their bodies. Worms, on the other hand, do get nutrition out of the dirt they eat. They can do this because the vitamins and nutrients in dirt are already fairly broken down, so the worm doesn’t need to do much chewing or digesting before absorbing them. That’s the problem with digesting rocks: most animals have no way of breaking them down into small enough components to be useful in the body.
But we’re not done yet! One sea creature, the rock-boring urchin, does chew up rocks: It digs tunnels in reefs to make its houses, by literally chewing through the stone, eating their way to the creation of the tunnel. And these urchins eat a lot of rocks: the equivalent of a human eating 500 pounds of rock per day.
As you can imagine, these creatures have very hard teeth. They have to, if they’re literally chewing through stone without damaging their teeth. These teeth are made out of mineral crystals bound together with calcium. Crystals tend to be very strong due to their organized chemical structure: that’s why diamond is one of the hardest substances in the world. So, if you want to chew through rock you need hard, crystalline teeth. Starting to sound like Sableye, eh?
These urchins might be the closest thing to Sableye in our world. They chew through rocks, parts of their bodies are made out of crystal, they live in caves (that they dug with their own teeth). It is important to note that these urchins also eat algae, and that’s where most of their nutrients come from; not from the rocks. Animals need a lot of material to upkeep their body. Rocks may contain certain minerals, but proteins and amino acids and organic substances animals need to survive simply aren’t found in rocks. Even Sableye can’t survive on rocks alone: it eats rocks for the crystalline parts of its body, but it must get other nutrients from other sources.