This urchin is a deep maroon colour and shaped like a domed limpet.

This is fringed by a ring of large, flattened modified spines.

On the underside there is another ring of smaller flattened spines and a large number of tube feet.

[2] This urchin is usually found on substrates fully exposed to waves and their associated abrasive effect, often in groups.

A combination of their shape, their flattened spines and particularly the strong adhesion of their tube feet made them three times as resistant as other species such as Echinometra.