Characters: Colonies are flat and are frequently lobed, up to 3 m across in high latitude localities, usually smaller in the tropics. Corallites are 2-4 mm diameter. Paliform lobes form a neat circle around small columellae. Tentacles are sometimes extended during the day; they are short and are of two alternating sizes.
Colour: Yellow, cream, green or brown, usually pale colours in the tropics and bright colours (green or brown) in high latitude areas.
Habitat: Occurs in most reef environments but especially in shaded places such as under overhangs. Also occurs on rocky foreshores of temperate locations protected from strong wave action.
Abundance: Seldom common.
Identification Guides: Randall and Myers (1983); Veron (1986a); Sheppard and Sheppard (1991); Nishihira and Veron (1995); Coles (1996); Carpenter, Harrison, Hodgson et al. (1997); Pillay, Terashima, Venkatasami et al. (2002); Chan, Choi, McCorry et al. (2005); Pichon, Benzoni, Chaineau et al. (2010); Turak and DeVantier (2011b);