Sea urchin

Echinodermata – Echinoidea


Known as a sea egg, this hollow-shaped ball is actually the internal skeleton or test of a sea urchin. When alive, the test is covered with spines, which help the urchin to move around, as well as protect it from predators. The spines break off when the urchin dies and the empty tests wash up on the beach.

Beached urchin test

Did you know?

Sea urchins are grazers, feeding on encrusting organisms such as sponges and algae. Their mouth is in the centre on the underside and contains a set of jaws and horny teeth, named Aristole’s lantern.