Shell is the mantle of the mollusk. It has a special kind of gland cell, whose secreta can form the calcium compound which can protect its soft body, called shell. The number, shape and structure of the shell are very different. The main component of shell is 95％calcium carbonate and a small amount of shell quality. Shell is divided into 3 layers. The outmost layer is dark brown cuticle (shell skin) formed by the shell quality secreted by the mantle edge. It is thin and transparent and can prevent the erosion of carbonate. The middle layer is prismatic layer which is thick, and it is formed by the prismatic calcite secreted by the rim of the mantle. The out and middle layer increase the size of the shell, but without increasing the thickness. The inner layer is nacre (bottom layer), and it is formed by the foliated aragonite secreted by the mantle. The nacre has beautiful luster, and it is thicker with the body grows.

Pearl powder contains a large amount of calcium carbonate, and trace elements needed for animals, such as Cu, Mg, K, Mo, P, Mn, Fe, Zn, and etc. The nacre contains a large amount of amino acid.

Mainly applied in: feed additives, environmental friendly fertilizer, crops, calcium in medicine, high-grade decoration coating, soil improvement, jewelry processing and other industries.