Biomineralization

...is the process by which organisms induce or control mineral formation from ions in solution. Calcium carbonate biominerals are particularly significant because of their direct role in regulating the global carbon cycle, as well as their ubiquitous occurrence across earth environments. Biogenic carbonates are further distinguished because the appearance of calcifying organisms in many different branches of the phylogenetic tree cannot be explained through a common ancestor. Rather, the fossil record shows that eukaryotes evolved the ability to control carbonate nucleation and growth at least 28 separate times (Knoll, 2003, in Biomineralization, RiMG v. 54). It has been suggested that these unrelated eukaryotes must have deployed "off the shelf" biochemical strategies to control mineralization (Knoll, 2003). This implies that many eukaryotic organisms must share similar, fundamental mechanisms to initiate growth and is consistent with the general idea that organisms use biochemical commonalities to create templating structures that guide the formation (nucleation) of some biominerals.