Common morpho butterflies have brightly-colored, blue metallic upper wings. Their undersides, visible while the butterfly is at rest, are cryptic camouflage featuring 4 sets of "eyespots." The metallic colors are products of iridescence, not pigment; the scales covering the wings (almost all lepidoptera have scale-covered wings) reflect incident light repeatedly at successive layers, leading to interference  that most effectively yields wavelengths in the green-blue range (450-550 nm), depending on the angle at which they are viewed. Many creatures great and small exhibit iridescence, and it has been shown to have evolved independantly in several instances.