Scientists have been studying a beetle whose scales are, 'just 5 microns thick that act as three-dimensional photonic solids—materials that manipulate light. Internally the scales are "a random network of interconnecting cuticular filaments," the article says. It's the randomness that does the job, apparently. Those filaments (in conjunction with the air gaps between them, says a good summary on Scientific American's web site today) bounce light around just right to have whiteness and brightness comparable to human baby teeth and treated paper.' (from Wired News)