Animals can appear colored due to two mechanisms, pigments and structural colors. Animals may have both biological pigments and structural colors, for example, some butterflies with white wings. Animals can also appear coloured due to structural colour, the result of coherent scattering perceived as iridescence. The structures themselves are colourless. Light typically passes through multiple layers and is reflected more than once. The multiple reflections compound one another and intensify the colours. Structural colour differs according to the observer's position whereas pigments appear the same regardless of the angle-of-view. Animals that show iridescence include mother of pearl seashells, fish, and peacocks. These are just a few examples of animals with this quality, but it is most pronounced in the butterfly family.