Life Fibers (生命戦維 Seimei Sen'i?) are sentient parasitic organisms of extraterrestrial origin, and are the origin of all clothing on Earth, as well as the entities responsible for the evolution of humanity. All Life Fiber originates from the Original Life Fiber (原初生命戦維 Genshō Seimei Sen'i?), an object originated from space that crashed onto Earth tens of thousands of years ago.
The Original Life Fiber was supposedly destroyed when Ryūko and the S.S. Naked Sun cut through its core in episode 23. In episode 24, it approached Honnōji Academy in an liquefied form and wrapped itself around the missile that was in the center of the academy. It was torn off the missile by Ira Gamagōri and the missile was destroyed by the Nudist Beach's "Ultimate Double Naked DTR." Ragyō told Nui to "cast her body away" and so the Original Life Fiber latch on to Nui's lifeless head and absorbed it. Nui then took control and "wears" the Original Life Fiber in which Ragyō then absorbs it and morph herself to a missile, where she use it to go to the REVOCS satellite in space. The Original Life Fiber is completely depleted from existence when Ryūko takes "Absolute Domination" for herself, eliminating Ragyō's Shinra-Kōketsu.