In nature, habitats often display breath-taking colours because plants and animals use colours for a variety of purposes including photosynthesis, camouflage, thermoregulation, communication, to attract pollinators, and for courtship. Most of these colours come from embedded pigments, dyes or molecules [1]. The green of plants, for example, is caused by chlorophyll absorbing light mostly in the blue and red regions of the visible spectrum. Only green light is scattered, which produces the green colour of leaves. However, in some cases natural colours are the result of nanostructures [2]. A textbook example of this is nacre, a substance that molluscs secrete ...