Characters: Colonies are upright, irregular, usually contorted, anastomosing bifacial plates. They are often over one metre across. Columellae are wall-like lobes.
Colour: Deep bluish-grey or brown.
Similar Species: Pachyseris gemmae. See also P. involuta.
Habitat: May develop into large mound-shaped colonies in shallow water but smaller colonies occur in a wide range of habitats including those exposed to strong wave action.
Abundance: Common.
Taxonomic Note: A species complex.
Taxonomic References: Veron and Pichon (1980); Veron (2000a);
Identification Guides: Veron (1986a); Nishihira and Veron (1995); Turak and DeVantier (2011b);
