TIL about structural colouration. ‘Structural coloration in animals, and a few plants, is the production of colour by microscopically structured surfaces fine enough to interfere with visible light instead of pigments…’

https://en.wikipedia.org/wiki/Structural_coloration

https://www.reddit.com/r/todayilearned/comments/15j2nrz/til_about_structural_colouration_structural/