Sand Dollar
Sand dollars are members of the group of spiny-skinned marine creatures called echinoderms (i-KIE-nuh-durms). Within the echinoderms, sand dollars belong to a large and diverse group, ranging from the tiny pea urchins to sand dollars the size of dinner plates. There are about 150 living species of sand dollars, and about 750 known fossil species. Their closest relatives are sea urchins. However, unlike them, sand dollars have a flattened body and much smaller spines that form a dense, velvety covering.