It is distinguished by having just four calcified shell plates. Its body is low and cone-shaped featuring a large, diamond-shaped opercular opening. In younger individuals, the shell plates are smooth with a central notch along the bottom edge of each plate. As the barnacles age, the plates develop prominent vertical ridges, resulting in an uneven, roughly circular outline. Juveniles display an opalescent greyish-white color, while adults turn a dull greyish-brown and show signs of surface erosion.