Diatom cells are enclosed within porous silica walls that exhibit a wide variety of forms. Some of them exhibit photonic crystals properties arising from a periodic distribution of pores along these walls. Diatoms then play with solar light to protect the cell and improve its photosynthetic properties. These micro-algae also suggest that life is possible inside a glass box leading to the bio-inspired synthesis of living materials via the so-called sol-gel process.