- The tough chitinous external covering regarding the shell of numerous mollusks, specifically freshwater ones, that shields the layer from erosive action of water.
- The proteinaceous external sheath of many molluscan shells.
- A chitinous membrane layer covering the outside of many shells; -- labeled as additionally epidermis.
- The horny epidermal financial investment associated with the shells of all mollusks.
Sentence for "periostracum"
Form for "periostracum"
Variant for "periostracum"