Colonies are phaceloid with corallites circular or flabello-meandroid with short valleys. Valleys are up to 40 millimetres wide. Corallite walls are sharp edged. Septa are closely compacted. There are no columellae. Tentacles are short and fleshy and covered with short uniform branchlets, each with a terminal knob. They are aligned radially to polyp centres and can retract, but only slowly.
Usually a distinctive purple-grey, sometimes greenish-grey, occasionally translucent. Branchlets sometimes have pale tips.