Keyhole Urchin (Mellita quinquiesperforata)
The keyhole urchin sand dollar gets its name from a keyhole-shaped perforation toward the rear of the endoskeleton
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.