A male Indian Peacock at the Franklin Park Zoo, Boston, Massachusetts.

Often used as a metaphor for color, posturing, male sexuality and... well... the gay community, one of the male Peacock's best-known features is it's outsized, predator-attracting tail.

While the gynormous tail is undoubtedly a burden in the wild, for the peacock, like the turkey and the pheasant, doesn't have enough muscle power to fly for more than short bursts, the animal nonetheless gained it through natural selection.
This animal is often used as an example of evolution in action. How a feature can be so seemingly useless and yet so thoroughly long-standing throughout untold peacock generations for no other purpose than it's use as a lure for sexual reproduction.