Colonies are submassive or form thick laminae. They may be over one metre across. Corallites are large (up to 15 mm diameter) on older parts of colonies, becoming smaller towards the periphery of laminae. Large corallites may be up to 15 millimetres exsert and occasionally have daughter corallites budded from their walls. Peripheral corallites are usually inclined towards the margins of laminae. Costae are large and have few if any teeth. Septa and columellae may be twisted into a short spiral.