If you're ever on the coast of Chile or Peru, you might come across one of the strangest creatures this world has to offer. You probably won't be able to spot it, because it looks like a normal rock, but it is so much more than that. The Pyura chilensis is a living creature that totally looks like a rock, which explains its nickname, "the living rock." Again, it's not a rock, but good luck believing that until you see what it looks like when it's cut open. The Pyura chilensis might look like a rock, but it's actually a...