Scientists generally explained chameleon color change as pigment, or colored chemicals, spreading out or bunching up inside skin cells. A 2015 study of panther chameleons found something different.
Their skin holds a layer of tiny see-through crystals. When a male gets excited, such as in a contest with another male, the crystals move farther apart.
That changes which colors of light the layer reflects, so the male's green skin turns yellow or orange.