Figure 5. The general physical appearance of Coronula diadema. They are about 6cm in height and 8cm in width. A) The side view of a C. diadema barnacle. Transverse ridges can be seen especially abundant at the lower portion of the barnacle and longitudinal ribs can also be discerned on the surface of the shell. (Adapted from Cornwall 1924). B) Top view of the barnacle. The operculum is reduced in this species. C) Bottom view of the barnacle. The bottom of the shell is concave-shaped. (Photos B and C are adapted from Hayashi 2011).