Pearl mussels and river mussels are two different species, and pearls cannot be grown through ordinary breeding. Generally, there are no pearls in river mussels. Of course, some river mussels have pearls in them. Naturally, foreign objects or gravel accidentally entered the mussel's mantle and epidermis, and the mussel cannot spit it out. Over time, the cells and tissues inside divide and multiply into pearl sacs. , layers of secretion packages form pearls. For culture, the species directly chooses the pearl mussel. There is a machine that can directly bury materials into the shell when the mussel is young. Usually, plastic or specific particles are implanted into the pearl mussel and then released. After such a small operation, pearls are produced. ~