Two dark colour Sand dollars in a beige lacquered wood base.
The Sand dollars are species of flattened, burrowing sea urchins belonging to the order Clypeasteroida. Echinarachnius parma, the Common Sand Dollar, is widespread in the Northern Hemisphere, from the intertidal zone to considerable depths. Sand dollars can be found in temperate and tropical zones, these come from Florida – USA.
All sand dollars have a rigid skeleton known as a test. This is the typical white disk found washed up on beaches. The living animals have a skin of movable spines on the test. The sand dollars are the most specialised sea urchins. All their features are adaptations for burrowing. They live just beneath the sand, either flat or at an angle. At an angle they keep the edge facing the oncoming currents, presumably to catch food. Sand dollars can live for up to 10 years. Most living sand dollars have dark colours, like brown or purple. Their darker color helps them stay camouflaged, easily hiding in the sand or mud or on the sea floor. The tests of sand dollars do not have bristles and tube feet, and because of the sun, they usually become bleached white.