Characters: Colonies are phaceloid to plocoid, and consist of a few to large numbers of corallites. Corallites are less than 7 millimetres diameter. Septa are mostly in two cycles of which only the first reaches the columella. Septa have slightly serrated margins. Primary septa may be exsert. Columellae are poorly developed. Mantles, but not tentacles, are extended during the day and may form a continuous surface obscuring the underlying growth-form. Colour: Commonly dark red with conspicuous green oral discs. May also be pink, orange, brown or uniform dark grey with white margins to primary septa. Similar species: Blastomussa wellsi, which has much larger corallites with more numerous septa. See also the faviid Parasimplastrea sheppardi, which is cerioid and has extensive ‘groove and tubercle’ formations. Habitat: Reef environments, especially where the water is turbid. Abundance: Uncommon.