Silicon in life: whither biological silicification?

In my opinion, the last decade or so has seen a golden era of research into the many facets of biological silicification. The contents of this volume are testimony to recent advances in the field (Müller and Grachev 2008). The successes should be carried through into the next 10 years during which time the processes involved in the biomineralisation of silica ought to become as well understood as they are for calcium and iron-based biominerals. Of course, the reason why progress in biological silicification has been relatively slow is an apparent lack of appropriate chemistry to explain myriad forms of seemingly diverse examples of the deposition of silica in biota. In this Chapter, the title of which is a paraphrase of Voronkov et al.'s great work, Silicon and Life (1975), I have tried to provide plau sible bioinorganic solutions to biological silicification. Ideas are presented in the context of the evolution of biological silicification and are discussed, in the main, naively without specific reference to published research which might either refute or support their validity. (This serves as an apology to the many excellent scientists whose work has not been but should have been cited!) I hope the ideas presented herein demonstrate that, rather than acting as a barrier to understanding biologi cal silicification, the limited, biologically significant, chemistry of silicic acid is actually sufficient to act as a platform for future research in the field.