Characters: Colonies are encrusting to massive and are usually over one metre across. Corallites are 3-4.5 millimetres diameter, with numerous septa tightly compacted giving a smooth surface. Septa are uniformly separated and reduce in number from the wall to the columella without forming many fan-like fusions. Colour: Usually light reddish-brown. Similar species: Corallites are larger than any other Siderastrea. Habitat: Shallow reef environments. Abundance: Common.