Marine shell calcium is mainly calcium carbonate, which is one of the sources of calcium in calcium supplements. 1. More than 95% of the composition of marine shells is calcium carbonate, the rest of the other components are organic matter, trace elements (zinc, magnesium, phosphorus, silicon, iron, potassium, etc.). 2. Generally marine shells can be used as a source of calcium in calcium supplements. For example, scallops, oysters, pearl oysters, etc. from unpolluted sea area can be baked and dissolved in water to form calcium oxide solution, or prepared into biocalcium powder containing appropriate amount of active calcium through calcination process, or water-soluble ionized calcium can be obtained by dissolving shellfish in acid, and then prepared into calcium citrate, calcium malate complex, etc. 3. In addition, marine shellfish calcium can also be used in the production and preparation of food detergents and thermal insulation composite materials.