茧

例句：

1. 1. The cocoon of the silkworm is a protectiveshell formed during its development.
   蚕的茧是蚕在发育过程中形成的保护性外壳。
2. 2. The cocoon of the butterfly is a protective shell formed during itsmetamorphosis.
   蝴蝶的茧是蝴蝶在变态过程中形成的保护性外壳。
3. 3. Thecocoon of the caterpillaris a protective shell formed during its transformationinto an adult.
   毛毛虫的茧是毛毛虫变态成成虫时形成的保护性外壳。