Shine an ultraviolet light on a chameleon in the dark, and it will light up with an eerie blue glow. It’s not their color-changing skin at play here, either. It’s their bones.

It’s long been known that bones fluoresce under ultraviolet light, some researchers have even used the property to find fossils, but our bones are usually all covered up. To let the light out, chameleons have evolved rows of small bony outgrowths along their skeletons that sit just beneath the skin, making it thin e