Typically large (> 40 mm diameter) colonies of hemispherical to ovoidal or spheroidal shape which when sectioned exhibit conspicuous concentric layering. Colonies are composed of numerous cup-shaped subcolonies fused at their edges. The surface appearance of colonies varies according to the developmental state of the constituent subcolonies: colonies with fully developed subcolonies are covered by ridges in a polygonal pattern, each ridge marking the junction between two subcolonies; colonies with partly developed subcolonies have a relatively flat surface with indistinct polygons marking subcolony boundaries; colonies budding new subcolonies have polygonal ridges with small, subcircular subcolonies developing on their tops. Lower surfaces of subcolonies are transversely wrinkled, and boundaries between fused subcolonies are strongly corrugated (as seen in thin sections and some fractured specimens). Upper surfaces of subcolonies are covered by the polygonal apertures of autozooids and kenozooids.
Autozooids are tubular with apertures about 0.11 mm in diameter, sometimes slightly salient and arranged in indistinct radial rows. Internally, autozooecia occasionally have transverse partitions (diaphragms).
Kenozooids are also tubular with polygonal apertures but the apertures tend to be slightly smaller and less prominent than those of the autozooids.
Gonozooids are developed at the centres of a minority of the cup-shaped subcolonies. They are distinguished as flat areas formed by smooth calcification (exterior wall) that is pierced by scattered, subcircular autozooidal apertures. Internally, vertical septa-like walls may incompletely subdivide the gonozooid.