enlarged, thorn-like denticles. 
Circular bumps along the flippers, dorsal fins or heads of some cetaceans.
Warts.
small knobbles on the surface of echinoid and trilobite bodies. On echinoids they are attachment sites for spines which are adapted for protection and movement. On trilobites they are thought to have had a sensory purpose
Small tubes or tuber like bodies.
Circular bumps along the edges of the flippers and dorsal fins of some cetaceans; also the knobs on a Humpback Whale's head.