Sculpture on a mollusc shell is the pattern or ornament of ribs, nodules, growth lines, and other distinguishing marks, which are useful in identification of the species in question. Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Various seashells The hard, rigid outer calcium carbonate covering of certain animals is called a shell. ...

The following are terms applicable to the sculpture of a molluscan shell:

• Axial sculpture - Sculpture running parallel to the axis of coiling. The Axis is an imaginary line through the apex of a gastropod shell, about which the whorls are coiled.
• Bead - A small hemispherical protuberance resembling a bead, similar to but smaller than a nodule.
• Beaded resembling rows or strings of beads.
• Growth Line(s) - fine transverse lines marking growth of the shell.
• Lirate - ornamented with fine thread-like lines or grooves.
• Longitudinal sculpture - following the direction of the axis of the shell.
• Nodule - A rounded protuberance on the shell sculpture; larger than a bead.
• Nodose, Nodulose or Nodular - bearing small rounded protuberances or tubercules.
• Ornament - Can refer to surface sculpture standing out in relief on shell surface; or simply to sculpture as a whole.
• Pustule(s) - very fine knob-like protrusions, smaller than a tubercule.
• Reticulate - sculpture consisting of a criss-crossing network of riblets, threads, or grooves.
• Rib - a strong ridge on the surface of the shell.
• Riblet - smaller than a rib, but coarser than a thread.
• Spiral sculpture - Sculpture following the spiral growth of the shell.
• Stria (Pl. striae) - a shallow incised groove.
• Striate - ornamented with striae.
• Thread - a very fine riblet.
• Transverse sculpture - sculpture parallel to the edge of the outer lip of the aperture.
• Tubercle(s) - Elevated knob-like projections or protrusions; larger than pustule.
• Varicose - Bearing a varix or varices.