Diatoms are single-celled algae that possess silica shells called "frustules" decorated with periodic structures ordered at the micro-and nanoscale. Diatom biosilica containing metabolically inserted germanium is used to fabricate an electroluminescent (EL) thin film device (see figure). The EL spectrum has a series of sharp UV line emissions at 340-380 nm and weaker bands in the blue and red range.