A lid or flap covering an aperture, such as the gill cover in some fishes or the horny shell cover in snails or other mollusks. 鳃盖覆盖在一孔或缝隙上的盖，如一些鱼类的鳃或覆盖在蛇或其它软体动物身上的角质壳
Any of various mollusks that bore into soft rock or wood. 钻蛀虫钻入松软岩石或木头中的软体动物
A smooth, lustrous, variously colored deposit, chiefly calcium carbonate, formed around a grain of sand or other foreign matter in the shells of certain mollusks and valued as a gem. 珍珠在几种软体动物的贝壳中，围绕着一粒沙子或其他外来物质形成的一种光滑、有色泽、具有不同颜色且主要是碳酸钙的沉积物，被珍视为宝石
