Definition: Internal supports as in sand dollar buttresses and ammonite, anthozoan, bryozoan, and archaeocyathid septae, less than the thickness of the shell/carapace.
Definition: 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.
