Sand Dollar Shells on Wet Sand

The white sand dollars people pick up on the beach are skeletons. A living one is covered in short, velvety spines, usually purple or brown, which it uses to creep through the sand. The five-petal pattern on top marks rows of tiny tube feet the animal breathes through. Sun and surf strip the spines off once it dies and bleach what is left. Three of these old skeletons lie half sunk in wet sand at the edge of the tide here, one with a chipped rim. As a sand dollar jigsaw puzzle it is mostly soft grays and creams.