The properties of biological materials are surveyed to point out those areas where we might expect to improve synthetic materials by introducing structures seen in biology. Biological ceramics and composites have properties which could be desirable in the equivalent synthetic materials. Progress has been made towards making biomimetic materials by in situ precipitation and by other methods. While the microstructure are being made which resemble those of shell and bone, the properties of the synthetic materials are still not good. The key missing factor is probably control of the interfacial boding. Controlled mineralization on surfaces could be used to manufacture devices. Our knowledge of how biomineralization is controlled is still too limited to be applied to synthetic systems. Possible control mechanisms are discussed and recent experiments reviewed.