常见例句For the middle layer shell (ostracum), also known as the prism of the (primatic layer) accounted for most of shellfish from Jiaozhuang calcite (cacalcite) pose. 外层皮肤从背部折皱成一层皮膜，叫做外套。外套把身体包围起来，并分泌出石灰质。 返回 ostracum