Echinocyamus pusillus, commonly known as the pea urchin or green urchin, is a species of sand dollar, a sea urchin in the family Fibulariidae, native to the northeastern Atlantic Ocean and the Mediterranean Sea. It buries itself in gravel or coarse sand at depths down to about 1,250 m (4,000 ft).

Description Echinocyamus pusillus is a small sea urchin with an oval, flattened body measuring up to 15 mm long.

Echinocyamus pusillus Description: A tiny oval, flattened sea urchin which lives in coarse gravel. When alive its colour is grey-green but on being hurt or damaged it turns bright green. The spines are short and give the animal a velvet texture. The anus is on the underside of the test posterior to the central mouth. Typically only 1cm. in length.