Rock-Boring Urchin

Care at a glance

Overview

Give it a tank of 75 litres or more at 22 to 27 C and pH 8.1 to 8.4 with plenty of rock and algae to graze. It eats film algae, hair algae, and coralline, and will take nori or algae wafers if the tank runs low on natural growth. It is a strong grazer that can bulldoze loose frags and wedge into rockwork, so glue down corals and expect it to rearrange small pieces.

In the wild

This is a hardy dark urchin with short, thick spines and a test around 5 cm across. In the wild it grinds a snug hollow into rock and sits in it by day, coming out at night to graze algae close to home. Colors run from near black to brown, green, or reddish.

Good to know

Echinometra mathaei is one of the most common reef urchins across the Indo-Pacific and can occur in huge densities on some reefs. Its jaw apparatus, called the Aristotle's lantern, lets it rasp both algae and rock.

Did you know

It can slowly excavate a burrow into solid limestone rock, grinding away with its spines and teeth until it has a hollow that fits its body.

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