Both the dorsal and ventral surfaces are smooth and have no dermal denticles. Chondrichthyans have toothlike scales called dermal denticles or placoid scales. It had an elongated snout lined laterally with barbed "teeth", or denticles. Shark skin is composed of periodically arranged diamond-shape dermal denticles, superimposed with triangular riblets. Their scales, called dermal denticles, and teeth are homologous organs. The dorsal side of the head has its own collection of denticles which point posteriorly. The complex itself is covered in up to nine rows of large denticles pointing anteriorly. The skin is densely covered by small, overlapping dermal denticles. Tooth enamel is found in the dermal denticles of sharks. The skin is densely covered by minute, overlapping dermal denticles. The skin is thick and covered by well-calcified dermal denticles. The skin is covered with closely placed dermal denticles. Most species have rough skins with dermal denticles which are especially obvious along the spine. As with the premaxilla, the predentary of "Eolambia" bore denticles. Their rims are stiffened with chitin and may contain minute toothlike denticles.