Crystals and Life: An Introduction

Living organisms of all sorts, whether single cell or complex multicellular, plant or animal, have the capacity to utilize metal ions obtained from their environment and form them into diverse structures with diverse uses. The formation of these mineral aggregates, generally considered as "biomineralization," requires the intervention of the host organism for the selection of the ions acquired, for the size, shape, crystal structure, and mechanical properties of the particular mineral formed. The biota, whether on land or in the waters, utilize macromolecules that they produce to mediate and regulate their biomineralization processes. The mineral-organic composites formed can thus be tuned to the purposes of the mineral, whether to form an exo- or endoskeletal structure, whether it is to be permanent or transient, whether it is to be high in tensile or compressive strength, or an extra- or intracellular storage depot for selected ions.