They are classified within the dinoflagellate group Dinophysiales, indicating they possess armored plates. These organisms have a pellicle, which serves as a shell, formed from the cell membrane and vesicles. These vesicles are composed of cross-linked cellulose, creating the plates. The pellicle divides into two structures referred to as the epicone and hypocone, located above and below the transverse groove, known as the cingulum, respectively. Surrounding the epicone and hypocone are two rows of plates arranged in a specific pattern, which may be inherited by offspring. These patterns are often utilized for species identification.