porphyry shell

porphyry shell (plural porphyry shells)

1. The shell of a particular marine gastropod known as the tent olive (Oliva porphyria), having a dark red or brown polished surface, marked with light spots, like porphyry.

• “porphyry”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.