Nature has mastered the art of precise nanoscale engineering.A striking example of this is found in the single-celled, marine microbes known as diatoms, which encase themselves in an ornate cell wall made of silica.The intricate, nanoscale architecture of the diatom shell is a rich source of inspiration for materials chemistry as it remains difficult to synthesise these ordered, hierarchical silica structures in the laboratory, particularly under physiological conditions without recourse to extremes of temperature and pH.