Colonies are composed of fused horizontal branches, forming small tables. Branchesusually have upturned ends which taper to a point. Corallites on horizontal branches are mostly immersed; those on upright branches are usually of two sizes, the larger being tubular, with sharp edges. Skeletons have a permanent dark colour.
Usually bright or pale blue or brown.
Turbid or clear water on upper or lower reef slopes.