Definission: Pointed, typically elongate appendages on the shell or carapace surface, less than the thickness of the shell/carapace and covering a small area of it.
Definission: Repeated, thickened, raised structures on the shell or carapace surface, less than the thickness of the shell/carapace and covering a small area of it. Thickenings can be either radial, comarginal, axial or spiral.
