Maybe their moms told them nobody likes a showoff. That would explain why many species of chameleon are hiding fluorescent bone bumps on their heads that scientists only just discovered. Chameleons also have independently moving eyeballs, superlative tongues and sophisticated color-changing skills. The animals might use their glowing head bumps as signals to each other. These patterns of dots are invisible to a human eye, but may light up deep blue to the eye of another chameleon in a shaded