Whether it’s to hide from predators, to attract mates, or to frighten rivals, changing colors is more than just a neat trick for chameleons. It’s key to their survival. But just how the skin of these creatures shifts from red to gold to green and many colors in between has been something of a mystery, until now. Using electron microscopy, specialized videography, and some modeling, Michel C. Milinkovitch and coworkers at Switzerland’s University of Geneva found that panther chameleons (Furcifer pardalis), one of which is pictured here, alter their hue by tuning guanine nanocrystals within their skin (Nat. Commun. 2015, DOI: 10.1038/ncomms7368). By changing the spacing between these nanocrystals, the chameleons can alter which wavelengths of light their skin absorbs and reflects.