Feathers of a Palawan Peacock-pheasant (Polyplectron napoleonis)
Iridescence is cool already, but did you know that it is also fundamentally different from regular colors?
Iridescent colors, along with most blues and greens, are created in an entirely different way than what we think of as normal pigment coloration. Pigment colors are determined by the materials that make them up, such as melanin, beta carotene, or psittacofulvin (a unique pigment responsible for the reds, yellows, and orange colors in parrots). Conversely, these special colors, like iridescent ones, are determined by the microscopic structure of their material. I.E. it’s not a matter of what it’s made of but how it is shaped (or a combination thereof). Most vibrant blues, greens, purples, and some yellows are actually structural colors, whereas most reds, browns, blacks, and oranges are pigment colors.
For more info I suggest you visit the wiki page on structural coloration. I’ve seriously oversimplified here. But isn’t it beautiful!