Sand dollars eat tiny bits of organic material they find on the sea floor. Sand dollars are echinoderms, which means they have spines. They get the name "sand dollar" because their skeletons look like large coins when they wash up on the beach.
When sand dollars are alive, they are about 3 inches in circumference and have very small spines that give their bodies a velvety feel. They move about on tube feet, which also help them to dig into the sand, collect food and convey that food to their mouths. Sand dollars also have tube feet on top of their bodies. These feet help the animal breathe.