[wài ké]
hull; incrustation; outer skin; outermost shell; case; shell; jacket; package; housing; skin; sleeve; body; outer covering; outer casing; crust; sheathing; exochite
battery case
电池外壳
the outer casing of a thermos flask
热水瓶外壳
This kind of beetles have hard shell.
这类甲虫有坚硬的外壳。