Sand dollars are a kind of sea urchin – and like their spiky relatives, they’re also covered in spines… just very, very small ones.

The hard, bleached “sand dollars” you may see washed up on the beach are not shells, but are actually the skeletons of the sand dollar animal. While alive, sand dollars such as this species (Clypeaster subdepressus) are covered in small spines that feel like fuzz and help transport food to their mouths.

Sand dollars spend much of their time buried in the seafloor, emerging at night to feed on debris in the sand.

This sand dollar was collected collected off the coast of Bull Island and photographed by the Southeastern Regional Taxonomic Center (SERTC) at our Marine Center in Charleston.

See more images from SERTC’s collections here.