One traditional story about the sand dollar is that it is currency lost by mermaids or the denizens of the lost civilization of Atlantis. Other people have found religious symbolism in the animal's five-fold symmetry.Continue Reading
Sand dollars are echinoderms that live in the ocean. When the sand dollar is alive, it's covered with short spines that differ from the long spines found in its relatives, the sea urchins. Unlike the spherical sea urchin, the sand dollar is flat. When the sand dollar dies, however, it often washes up on shore as a chalky disk with a pattern in the top center that looks like five flower petals. The skeleton of the sand dollar is called a test and is made up of calcium carbonate.
Sand dollars live mostly buried in the sand in the area between high and low tides. They eat tiny bits of food that are washed their way by the ocean currents. Their mouths are on the underside of the body and are circled with spines and tiny hairs that catch the food and help convey it into the mouth.
Sand dollars are often found in colonies, which aids in reproduction, as the sexes are separate. Fertilization happens externally, and the larvae drift through the water until their skeletons form.Learn more about Marine Life