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.
Taxonomic Note: Siderastrea glynni described from the Pacific side of the Panama canal is probably this species introduced from the Caribbean.