After complete genome sequencing, the diatom Thalassiosira pseudonana has become an attractive model organism for silica biomineralization studies. Recent progress, especially with respect to intracellular silicic acid processing, as well as to the natures of the biomolecules involved in diatom cell wall formation, is described. On the one hand, considerable progress has been made with respect to silicon uptake by special proteins (SITs) from the surrounding water, as well as to the storage and processing of silicon before cell division. On the other hand, the discovery and characterisation of remarkable biomolecules such as silaffins, polyamines and--quite recently--of silacidins in the siliceous cell walls of diatoms strongly impacts the growing field of biomimetic materials synthesis.