Colony encrusting or erect, arising from an encrusting base and anchored by partially calcified, kenozooidal rhizoid system. Erect forms highly calcified, branching, bilaminar, sometimes fenestrate, often massive and very large. Zooids with umbonuloid frontal shield, with marginal areolae and central spiramen complex. Secondary orifice subterminal, with adventitious, oral avicularia; other interzooidal and vicarious avicularia typically present. Brooding in interior ovisacs of enlarged zooids with dimorphic orifices. (after Harmer, 1957, Bock & Cook MS).