壳质的

例句：

1. 1. The crab has a hard shell to protect its soft body.
   螃蟹有硬壳来保护它的柔软身体。
2. 2. The ship's hull is made of steel and has a strong shell.
   船的船身是用钢做的，有一个坚固的外壳。
3. 3. The turtle has a tough shell that protects it from predators.
   乌龟有一个坚硬的外壳，可以保护自己免受捕食者的伤害。