 "Ceratium" species belong to the group of dinoflagellates known as dinophysiales, meaning they contain armored plates.They contain a pellicle, which is a shell, that is made from the cell membrane and vesicles; vesicles are composed of cross-linked cellulose, forming the plates.The pellicle divides into two structures known as the epicone and hypocone that lie above and below the transverse groove, the cingulum, respectively.