- Main article: Seashells
In real lifeEditThe term sand dollar refers to extremely flattened, burrowing sea urchins belonging to the order Clypeasteroida. They have rigid skeletons known as tests that consist of calcium carbonate arranged in a fivefold radial pattern. Living sand dollars are covered in small hairs (cilia) that allow it to move across the seabed. Tests of dead individuals are often found on beaches, the textured skin missing, and the skeleton bleached white by sunlight.
The pores on the sand dollar are perforations in the endoskeleton which allow it to breathe. The mouth is located on the bottom of the body at the center of the petal-like pattern. The sand dollar is widespread in the Northern Hemisphere, at many different depths. In some folklore, sand dollars are said to represent coins lost by mermaids or the people of Atlantis.