The turbo shell operculum comes from the Turbo imperialis sea snail. The operculum is a corneous or calcareous structure like a trapdoor which is used to close the aperture of the shell when the soft parts of the snail are retracted. Opercula may be ground up and used to make incense and perfumes or as an organic "gemstone" in rings, bracelets, amulets, and other decorative ornaments.
The opercula measure 1.5" to 2" long and weigh between 21 to 36 grams (0.7 to 1.2 oz.).