The turtle's shell is divided into two sections&colon; carapace and plastron. The plastron is hingeless and slightly smaller than the carapace. They have an inflexible trunk encased in a horny carapace above and a plastron below. The species is identified on the basis of the structure of the carapace and plastron. The prosoma, or cephalothorax, is usually covered by a single, unsegmented carapace. The top one known as a head shield, dorsal carapace or H-element. Its most notable feature is the lack of a bony carapace. A ring of plates surrounds the body, homologous with the carapace of other crustaceans. The muscular abdomen has six segments and has a thinner shell than the carapace. The carapace and abdomen are transversely banded with alternative red and white. Christmas Island red crabs are large crabs with the carapace measuring up to wide. It contains the semicircular to subrectangular platelike carapace. It consists of a single sclerite situated between the coxa, opposite the carapace. The vertebrae attach to the carapace. The crab's bumpy carapace blends into the rocky ocean floor.