Specimens of three zoanthid species, Epizoanthus couchii, Parazoanthus anguicomus and P. axinellae were sectioned. All were gonochoric, with gametes developing during summer. Oocytes in P. anguicomus originate in a single-layered ribbon down the perfect septa, but the ribbon becomes moniliform as, at regular intervals, it folds laterally into lens-shaped nodes, packed with oocytes, doubling polyp fecundity.