What layers does a mollusk shell consist of?

The shell of mollusks consists of 3 layers. 1 outer layer, it is covered with a special substance “concholin” – this is such a horn-like substance that forms the outer layer of the shell. “. And the 3rd layer is the inner layer of the” heart of pearls “or mother of pearl and it is also wrapped with the same protein. By the way, the cells of the 2nd and 3rd zones in small amounts secrete our protein” concholin “, which serves as an” adhesive “material.