Characters: Colonies are submassive and usually lobed. They may be over 2 metres across. Corallites have irregular spiny walls. Polyps are often retracted during the day, but are elongate when extended giving colonies a mop-like appearance. Colour: Grey or pinkish brown when polyps are retracted, brown when polyps are extended. Similar species: Alveopora verrilliana, which can readily be distinguished by the palisade of spines around the corallites. Habitat: Exposed reef slopes. Abundance: Uncommon.