Hundreds of tube feet (podia) project from underside to capture and move food and sediment particles to the mouth.

Velvet-like skin of the live ones is usually tan, brown, gray or dark green. Turn white after death.

They burrow a few inches under the sand, and usually live in "herds" with a dozen or more others nearby.

Average life span: four years. Some may live up to ten.

Their mouths include a beak-like structure with five teeth. The rattle you hear when shaking one may be caused by these dried teeth inside.