Characters: Colonies are encrusting to massive and are rarely over one metre across. Corallites are cerioid or subplocoid, circular and have thick walls. Septa have long pointed teeth. Colonies have thick fleshy tissue over the skeleton which usually forms concentric folds. Colour: Uniform or mottled dull brown, grey or green, but sometimes brightly coloured. Similar species: Acanthastrea subechinata and A. brevis. See also A. hemprichii. Skeletons may be confused with those of the faviids Favites abdita or F. flexuosa, but underwater they do not resemble faviids because of the fleshy polyps. Habitat: Most reef environments. Abundance: Usually uncommon, but by far the most common Acanthastrea on tropical reefs