The very complex, biomineralized silica shells (frustules) of diatoms-autotrophic protists belonging to the heterokontophyta-are currently subject to investigations concerning the molecular mechanisms which precipitate silica and influence its morphogenesis. The formation of biominerals is fascinating because it occurs at ambient temperature, and because organisms are capable of efficiently manipulating mineral growth into forms and composite organizations that inorganic processes would never achieve. Recent results have shown that the growth of biominerals, including the silica-forming diatom shells, can be strongly influenced by the presence of diverse species-specific organic components. The geometry of biominerals and their interpenetration with macromolecules are defined by a production process which seems to be optimized for efficiency. However, it is not only the efficiency of this process, but also the quality of the product-the biomineralized structure-and its adaptive success which finally controls the details of biomineralization. Thus, it is argued here that it would be helpful to assess the function of biomineralized structures in order to understand the speciesspecific characteristics in the process of diatom biomineralization. Likewise, it is of interest to assess the physical properties of specific biominerals to transfer knowledge on biomineralization into diverse technological fields. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.