Colonies are submassive to massive, usually more than one metre across. Corallites are subplocoid, circular to irregular in shape, and crowded. The inner walls of corallites plunge vertically. Septa are thin, uniformly spaced and subequal, most reaching the columella deep within the calice. Costae of adjacent corallites do not meet, leaving a narrow ambulacral groove. There are no paliform lobes. Columellae are small and compact.