The cerithiid snail Cerithium coralium (Kiener), spawns from February to September in Vellar Estuary. The snail spawned in the laboratory without any inducement. The ribbonshaped spawn contains developing embryos enclosed in capsular wail. Maximum fecundity recorded was about 18,400 eggs in a single egg mass.

Early development involves formation of first polar lobe, polar body and second polar lobe in succession. Two-celled stage appears after two hours of spawning, and four celled stage after 4 hours. Trochophore stage is preceded by sterroblastula and gastrula stage. Veliger is formed within 24 hours, while hatching takes place after thirty six to forty two hours. Free veliger swims actively with the help of bilobed velar organs. Swim-crawl stage is attained by 12 days and larva settles as spat, when it is two and half when-led. The juveniles of five and seven whorled, lead benthic life with all adult characteristics. Intra-specific variations exist among the species of Cerithium in spawning periodicity, fecundity, size of the egg, development of embryo, hatching time and larval phase.