A sand dollar is a type of flat, burrowing sea urchin found on sandy ocean floors. They have a unique, round shape and are often gray or brown when alive. When they die, their shells can be found washed up on beaches, often bleached white by the sun. The intricate designs on their shells resemble flowers, making them popular among beachcombers and collectors. These fascinating creatures play an important role in their ecosystem. They feed on tiny organisms like plankton and help keep the ocean floor healthy. If you find a sand dollar, remember to treat it gently, as they are delicate and can easily break.