Characters: Colonies are massive, hemispherical or flattened and may be over 2 metres across. Corallites are round and of variable size, those on convex surfaces being larger than those on concave surfaces. Corallites are shallow, approximately 6-13 millimetres diameter, with tightly compacted septa. Columellae are large and small paliform lobes are usually developed.
Colour: Commonly blue-grey.
Similar Species: Phymastrea valenciennesi which has less compact, irregular septa. See also Favia species, especially F. helianthoides, which has corallites of similar size and shape.
Habitat: Protected reef slopes.
Abundance: Usually uncommon.
Taxonomic Note: Previously in the genus Montastrea/Montastraea. This species warrants a new separate generic designation.
Taxonomic References: Chevalier (1971); Veron, Pichon and Wijsman-Best (1977); Veron (2000a); Budd, Fukami, Smith et al. (2012);
Identification Guides: Veron (1986a); Sheppard and Sheppard (1991); Nishihira and Veron (1995); Chan, Choi, McCorry et al. (2005); Turak and DeVantier (2011b);
