Biominerals are produced in all five kingdoms. Calcium carbonate and calcium phosphate are the most abundant biominerals performing many functions including protection and skeletal support. The phylum Brachiopoda is divided into three subphyla: Linguliformea, Craniiformea, and Rhynchonelliformea (Williams et al., 1996). The Linguliformea possess inarticulated phosphatic valves. Articulation is also lacking in the calcitic valves of the Craniiformea while the calcitic valves of the Rhynchonelliformea are articulated. The paired valves of the brachiopod shell are one of the earliest examples of biomineralization. The existence of different mineral regimes and shell ultrastructures within the phylum makes the brachiopods ideal candidates for the study of biomineralization. The formation of brachiopod valves is an example of organic controlled mineralization, a term introduced by Lowenstam (1981) to describe biomineralization which is under genetic control via specific organic material controlling the precipitation and formation of the biomineral. In organically induced biomineralization (Lowenstam, 1981), organic molecules provide a nucleating surface on which mineral precipitates. Such precipitation continues as long as the solution is saturated with respect to the mineral ions. Stromatolite formation is an example of organically induced biomineralization. In brachiopod shell formation, organic molecules are not solely involved in nucleation. By binding to specific crystal faces, organic molecules inhibit growth along certain crystal axes and enhance growth in other directions, influencing the growth and formation of organically controlled biominerals. Finally, organic molecules inhibit biomineral growth. Thus, a suite of organic molecules is involved in brachiopod shell formation, their spatial and temporal presentation resulting in the formation of species-specific valves.