Operculum

n.	1.	(Bot.) The lid of a pitcherform leaf.
	2.	(Anat.) Any lidlike or operculiform process or part; as, the opercula of a dental follicle.
	3.	(Zool.) The lid closing the aperture of various species of shells, as the common whelk. See Illust. of Gastropoda.

Noun

1.

operculum - a hard flap serving as a cover for (a) the gill slits in fishes or (b) the opening of the shell in certain gastropods when the body is retracted

plate