Sand dollars add interest and diversity to a seashell collection or beach themed décor. The shell-like discs you might find washed up on the beach or purchase at a shore side souvenir shop are actually skeletal remains of animals, sometimes called a "test". The intricate design on the skeletons of these tiny cousins of sea urchins and starfish make them a beachcomber's favorite.
There are many different types of sand dollars. While the scientific names of these animals might be tongue twisters, they generally have charming and amusing common names. The "arrowhead" and "flat round" sand dollars are probably what you are accustomed to seeing in shell collections or on the beach. Other types include "sea biscuit," "sea gopher" and "pancake" varieties. They are all subspecies of the same sea animal class.
While a sand dollar is alive, the creature appears to have a fuzzy outer layer. This fuzz is actually very fine, minute spines. These spines allow the animals to tunnel under the surface of the sand. Their small mouths are near the center of the body, and they have tiny tube feet that allow them to move and feed. The animals are commonly found in clusters, creeping along the sand of shallow water, feeding on organic material.
Sand dollars are found on both the Pacific and Atlantic coasts of North America. They live just further than what is known as "mean low tide" and shallow water along the shoreline of the ocean. They prefer smooth sandy or muddy earth, living just on the surface of or burrowed slightly beneath the ocean floor. Depending on the region, you will find different varieties of sand dollars. The "western sand dollar" is found along the Pacific coast, while "keyhole sand dollars" inhabit the Atlantic coast.
Sand dollars look very much like their close relative, the sea urchin. They can range in diameter from the size of a dime to three inches in diameter. Sand dollars "tests," or skeletons, are white or off-white with a petal pattern much like its sea urchin cousin. The holes that create this pattern are actually pores. They are flat and round in shape, much like a cookie, disk or coin---hence the moniker, sand dollar.
Archaic lore taught children that sand dollars were "Mermaid Money." Greatly detailed, imaginative stories were spun about Atlantis-like cities where the mermaids spent their day shopping at fine underwater markets.
Christians find symbolism in the sand dollar. Both an Easter lily and a star---much like the biblical star of Bethlehem---can be found in the markings on the tests. The five narrow pores in the sand dollar are said to represent Christ's four nail holes and wounded side. The design on the bottom of the skeleton resembles a poinsettia. Also, when a sand dollar is broken, small bony pieces, resembling doves, fall out.