Corallum plocoid, its edge closely adhering to substratum. Upper surface low convex. Corallites exsert up to 10 mm, bent towards various directions. Calices round or oval; former up to 12 mm across, the latter up to 14 x 10 mm (without fission); many smaller corallites present. Wall thin. Intervening space between corallites varies from very narrow (almost absent) to 5 mm (some spaces appear very wide because of bending of adjoining corallites towards opposite directions).
Septa 40-60; thin, slightly thickened over mural rim; 4 cycles with the quarternaries appearing occasionally only as very low ridges. Joining of septa also found in some calices. Septa begin as narrow plates from calicinal rim with sharp teeth on their edges, gradually widen and, halfway down, suddenly expand and drop vertically into calicinal center. Expanded portion of primary generally entire while that of secondary is usually dentate. Septal surfaces finely granulate.
Costae thick, almost of same height; edges spiny, spines finer than those on septal edges. Even where septa are almost absent (quaternaries) corresponding costae are prominent. Costae usually suppressed on wide intercalicinal areas by abundance of vesicles (dissepiments).
Columella around a quarter of calicinal diameter, depressed, consisting of septal trabeculae.
