Sand Dollar Starfish, C. Humilis.

Sand dollars are a facinating relation to starfish and sea urchins, in appearance it is much like a flattened sea urchin with an oddly deliberate looking pattern resembling a flower.

Sand dollars are found on top of and in sandy and muddy soft areas of the ocean floor where they often bury themselves for safety and to forage; their diet consists of detritus, algae, infauna and suspended particulate matter that has settled on the sea floor. Although they typically spend their time on or in sandy areas I have noted them often scaling rocks and glass in home aquariums where they likely reap algaes and biofilms forming on those surfaces. It may be assumed that the airation and movement of the sand bed that occurs during their day to day activity is beneficial to the home aquarium in the same way as a sand sifting starfish is.