Characters: Colonies are columnar and/or thin horizontal or encrusting plates. Individual colonies are commonly mixtures of these growth-forms. Columnar growth-forms occur where wave action is strong, plates occur in protected habitats. Corallites are circular, plocoid and usually of irregular sizes. Those near plate margins may be aligned in parallel rows.
Colour: Pale or dark grey-brown or green, sometimes bright orange.
Similar Species: None.
Habitat: Shallow reef environments, especially those exposed to strong wave action, also on vertical rock faces and in caverns.
Abundance: Sometimes common.
Taxonomic Note: See Veron and Pichon (1980) for the history of this name.