Green sea-urchin has a spherical test, slightly flattened at the bottom side. The oral opening is placed in the centre of the bottom side. The have a rigid inner skeleton of closely joined plates with round knobs. The spines are attached to these knobs, allowing some flexibility. Tube feet are placed between the spines, used for walking and climbing.
It feeds mainly on algae that are grazed from the substrate.

The diameter is about 60 mm and the spines up to 25 mm long.

Beige, brown with pink to purple spine tips and tube feet.

From the sub tidal zone to a depth of more than 200 metres, preferably on hard substrate.

North Eastern Atlantic from Norway to the Azores, but not in the Mediterranean.