It can be found in the cell walls of fungi and the exoskeletons of shellfish, plankton and insects, along with insect egg cases and the powerful grinders and rigid walls in the pharynx of worms.

• 同样见于真菌细胞壁和甲壳类动物、浮游生物和昆虫的外骨架，多见于昆虫卵鞘和蠕虫咽部硬管壁和强有力的研磨器官。