The animal retracted into its shell.

这只动物缩回到自己的壳里。

《牛津词典》

So far, she and her colleagues have only excavated two small test pits at the cave, which contained a number of stone artefacts, bone points, animal remains, shell beads and fish hooks.

到目前为止，她和她的团队仅在洞内的两个小型试点进行挖掘，她们出土了一些石器、骨骼器具、动物残骸、贝类和鱼钩。

youdao

A protective covering, structure, or organ of an animal or a plant, such as teeth, claws, thorns, or the shell of a turtle.

防御器官动物或植物的防护层，结构或器官，如牙齿，爪子，荆棘或乌龟的壳。

youdao

He patted the animal on the shell, a little sorry to go.

NPR: Excerpt: 'Natives and Exotics'

He works on clams and is building robot versions of them to find out how the shape of an animal's shell affects its chances of survival.

ECONOMIST: Robots

And the way the skinny neck disappeared between the animal's breastplate and shell-a squirming, live thing slipping hidden into dead stony stuff-it seemed suddenly like the Mystery of Mysteries, the very source of Life .

NPR: Excerpt: 'Natives and Exotics'