Tiny crop circles made by sand dollars on the beach,” the Seaside Aquarium posted on their Facebook page, describing the photo shown. “Unlike sea stars and urchins who use tube feet for locomotion, ...

Sand dollars and their relatives (clypeasteroids, cassiduloids) have a bilaterally symmetrical test composed of TEN double columns of plates, five interambulacral columns (labelled 1-5) and five ...