Ostracod

crustaceans · ocean · tiny creatures · fossils

Shell like a seed.. Ostracods have two-part shells made of chitin and calcium carbonate that protect their bodies, kind of like a clam. These shells hinge at the top and can open and close to let the ostracod move and eat.

Incredibly small.. Most ostracods are only about 1 millimeter long, so you'd need a magnifying glass to see them properly. The biggest ones, like the marine Gigantocypris, can grow to 32 millimeters, which is still smaller than your pinky fingernail.

Picky eaters.. Ostracods have many different eating styles: some are carnivores hunting tiny prey, some eat plants, some scavenge dead stuff, and some filter food from the water. Most, though, are deposit feeders, meaning they munch on particles and bits of stuff on the ocean or lake floor.

Super diverse group.. Scientists have found about 33,000 different species of ostracods living in oceans, rivers, and lakes all over the world. They're grouped into 7 main orders based on the shape of their shells and bodies.