The term sand dollar refers to species of extremely flattened, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are known as sea biscuits. Related animals include the sea urchins, sea cucumbers and starfish. The bodies of adult sand dollars, like those of other echinoids, display radial symmetry. The petal-like pattern in sand dollars consists of five paired rows of pores. This image has been color enhanced.