noun

• (biology) Any external case or sheath.
• (botany) The pollen-producing organ usually found in pairs and forming an anther.
• (medicine) The twin layers of cells surrounding the basal lamina of an ovarian follicle.
• (microbiology, planktology) The membrane complex enveloping the cells of certain plankton including diatoms and dinoflagellates.
• (marine biology) The calcareous wall of a corallite, the exoskeleton of a coral polyp.
• (Christianity) A case for the corporal cloth used in the Eucharist.