shell

She found a tiny crab inside the empty shell. ▶

她在空贝壳里发现了一只小螃蟹。

Rising ocean acidity can weaken the shells of marine animals, threatening their survival and wider ecosystems.

海洋酸度上升会削弱海洋动物的外壳，威胁其生存以及更广泛的生态系统。