Most shells found at beaches were once part of a clam, snail or other mollusk. Flat ones with a pattern of holes resembling a five-petaled flower are however from a different animal – the sand dollar, a type of sea urchin. Sand dollars live around the globe in northern seas, on sand flats and deeper water.
Like other sea urchins, a sand dollar is covered with spines – in case a velvety coat of short, purplish spikes. The mouth, on the underside is equipped with chewing jaws. Tube feet, arranged in the shape of a flower, protrude through holes in the shell, which is known as test. They are used in breathing, feeding and moving about. A sand dollar travels with a wavelike motion of its feet and spines. It can be found in temperate and tropical zones.
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