Building products, chemicals calcium carbonate

Once die meat has been extracted, mollusk shells are usually discarded. Huge middens or piles of clam, oyster, and other shells disclose the appetite people have for these animals. Shells have sometimes been processed, either fresh or from middens, to provide calcium carbonate for a variety of purposes. Calcium carbonate has a huge number of practical uses in medicine, food production, chemicals, cosmetics, building materials, and many more. 

The third essential point of the cited publication also makes us realize that nature uses a very small number of compounds as building blocks (as demonstrated by the widespread presence of silica or calcium carbonate). But the natural design of these structures builds products of very diverse properties. The design differences are generally not chemical but structural. The important lesson for designers is that it is not the number of available monomers but their sequence and structural organization which imparts their unique properties. 

---