"Lotus effect", hydrophobic effect with self-cleaning ability
Close-up of the underside of a gecko's foot as it walks on a glass wall. (spatula: 200 × 10-15 nm).
REM scan of a butterfly wing scale (×5000)
Brazilian Crystal Opal. The play of color is caused by the interference and diffraction of light between silica spheres (150 - 300 nm in diameter).
Lycurgus Cup, glass, 4th century, Roman. Nanoparticles (70 nm) of gold and silver, dispersed in colloidal form, are responsible for the dichroic effect (red/green).