Corallum a thick, plocoid mass, high convex or hemispherical.
Corallites raised around 1 mm above general surface, circular, subcircular or deformed; full grown circular calice around 4 mm diameter; wall thin, not always distinct. Calicinal fossa cylindrical, 2.5 mm average depth but appearing deeper because of its shape and smaller diameter. Perithecal area 2 mm average width.
Septa 24-28 in full grown round calice, the three cycles very distinctly differentiated by their width; not very thick but appearing so by the prominent spines on their surface. Edges spiny especially the exsert portion, these spines lying on same rows as those on surface; vertical, even overhanging in most primaries; vertical edge with less prominent teeth than those of exsert portion. Exsert region forming rounded arch over calicular wall. Lower portion of septa with lamellate paliform lobes.
Costae equal in thickness, convergent. Columella papillose.
This species is distinguished from O. crispata by its relatively smaller, cylindrical calicinal fossa, its distinctly differentiated septal cycles, particularly the primaries, the very spiny exsert portion of the septa and the lamellate paliform lobes. Several specimens were obtained in shallow water inside a well protected cove, with partly muddy substratum.
It seems that Faustino’s illustrations (Plate 71, figs. 3 and 4) and those of Yabe, Sugiyama and Eguchi (Plate 42) are of this species.
