角质的，角蛋白的containing or made from keratin (= a strong natural protein, the main substance that forms hair, nails, horns, feathers, etc.)
The nail is a flat, keratinous, translucent structure. 指甲的结构是平面、角质、半透明的。
All cephalopods such as octopus possess a sharp beak, made of the same keratinous material as a bird's beak. 所有头足类动物，比如章鱼，都有一个喙，其角质材料和鸟类的喙一样。