Unlike its cousins, the starfish and the sea urchin, the sea cucumber seems woefully under-armored for the fish-eat-fish world it lives in. Starfish have bony plates made of calcium carbonate called ossicles to protect them, which is why they feel so tough. In sea urchins, those plates have fused together, and its bristling array of sharp spines further warn predators to keep out. But in sea cucumbers, those ossicles seem to have shrunk to near uselessness. This is great for the sea cucumber if it wants to, say, squeeze itself into a safe little nook in a rock or cranny in some coral—it can practically liquefy its body as it pushes into the hole. But that particular quality is not so useful for fending off a razortoothed attack.