Life Fibers are a race of extraterrestrial parasites that are responsible for the advancement of humankind, and they also contributed to the use of clothes and the need to cover oneself. The Life Fibers are a major plot point in the 2013 anime Kill La Kill, and are used by the antagonist of the series Ragyo Kiryuin as a means of dominating the world.
Long ago, Life Fibers would attach to its host in order to get nutrients, but eventually evolved to cover up the host's entire body. Later on, the Life Fibers went into a dormant state, and were later reawakened by Ragyo. Ragyo planned to use them in her plans on feeding humanity to them, and she gave up her humanity as well, and became very devoted to the Original Life Fiber, in which the other Life Fibers most likely spawned from.