Colonies are composed of encrusting, unifacial laminae which may become highly contorted forming hollow columns or tubes. A central corallite may be distinguishable. Corallites become more widely spaced towards the colony perimeter. They are irregular and usually outwardly inclined. Long and short septo-costae strongly alternate and are interlinked in complex patterns.
Dull grey, brown or green, usually with white margins.
Usually found on vertical or overhung walls in deeper water.