Of, pertaining to, or like, an operculum.

The principal opercular bone or operculum of fishes.

A covering/forming a covering. For female Janiroidean asellotan isopods the operculum equates to a plate over the branchial chamber of the abdomen consisting of the fused second pleopods (the first pleopods are absent in these isopods).

Over the gill plates

scale over the ear