"The micro-structure of a scale from a butterfly wing. Moth and butterfly wings use pigments to make some colours but physical structures, that affect the behaviour of light itself, to make others. The holes are around 1 micrometre across, about the size of a bacterium. Scanning electron microscopy by Dr Bronwen Cribb, University of Queensland."
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons, fans, zigzags, or stellate colonies.