Life Fibers

Life Fibers (生命戦維) 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), an object originated from space that crashed onto Earth tens of thousands of years ago.

History
Shortly after the Original Life Fiber appeared on Earth, Life Fibers began living as parasitic life forms, gaining sustenance from the biological life energy of other organisms. However, since the host could not withstand the strain of having them in their bodies, the Fibers began covering the host instead. As such, they targeted the ancestors of today's humans, which were the species with the mostly well developed brains at the time, and started accelerating their evolutionary process. With time, Life Fibers entered a dormant state, but left mankind with the evolutionary instinct to cover themselves. Twenty years before the events of the main story, Ragyō Kiryūin found the Original Life Fiber, causing the Life Fibers to awaken from their stasis, seeking to feed on human life.

Biology
Life Fibers are extraterrestrial organisms, originating from deep space outside of the Solar System, and possibly outside of the galaxy. The evolution of life fibers is unknown, however they are unique creatures that are vastly different from any form of life on Earth. They are multi-cellular microorganisms whose bodies grow in long thin strands, which radiate bright red life energy. These strands are very durable, similar to an organic metal. Life Fibers are parasitic organisms, living off the bio-energy that exists within the cells of the nervous system as well as in the circulatory system. They cover their host's body and bind to their peripheal nervous system instead of inhabiting their internal organs, to prevent killing them. The presence of Life Fibers can alter their host's DNA, which is how humanity evolved large brains, and is possibly how Goku Uniforms can give superhuman powers. Life Fibers also seem to be self-aware entities, capable of making decisions and thinking. Some life fibers are able to communicate with their hosts telepathically, probably by tapping into their nervous system. Life Fibers are also capable of manifesting new abilities in response to certain stimuli (usually life or death). Their ability to rapidly evolve is one reason why they are considered dangerous.

Use as a Material
Life Fibers are widely used in the production of clothing such as Goku Uniforms and Kamuis, although a small amount of Fibers are present in all clothing produced by Revocs Corporation, which accounts for 90% of the global market (As of episode 21, 100% of the global market). In Honnōji Academy, One-Star Goku Uniforms are composed of 10% Life Fibers; Two-Star Uniforms, 20% and Three-Star Uniforms, 30%. Kamuis are made entirely of Life Fibers. Hōka Inumuta is in charge of analyzing the Goku Uniforms researched by the Sewing Club.

In at least one occasion, experiments have been conducted by the Sewing Club, having a No-Star student wear a prototype Five-Star Goku Uniform. However, this caused him to become a huge muscular hulk and made him go berserk. Hōka Inumuta was able to restrain him. This demonstrates that certain people have a greater control over Life Fiber based clothing. Ryūko Matoi and Satsuki Kiryūin are such people, both being able to wear and control Kamuis.

Banshi
The Banshi (絆糸), or Nexus Thread, is a vital thread of Life Fiber present in every clothing made with Life Fiber. It is what holds them together, since it is, according to Shirō Iori, imbued with the will to 'cover'. It is protected by several layers of Life Fibers, making it nearly impossible to be located or damaged. If it is severed or removed, the garment is destroyed.

Though it is still unknown if this is a trait common to all Kamuis, Senketsu was shown to have multiple Banshi.

COVERS
COVERS (カバーズ) are Life Fiber embodiments. They are responsible for the dissemination of Life Fibers throughout the world. The name "Revocs" is an anagram after them.

COVERS can roughly be separeted into two groups: cloth-form COVERS and human-form COVERS. Cloth-form COVERS needs to stay in contact with the original Life Fibers in order to stay active, but human-form COVERS have absorbed a human being as an energy source and through that they can operate autonomously

According to Ragyō, the intent of COVERS is to "bind the heavens, the earth and mankind, covering all".

Trivia

 * The concept of living, parasitic clothing/armor is also found in the Spawn comic series. Al Simmons has a symbiotic relationship with K7-Leetha, a living suit that is actually a neural parasite from Hell made of necroplasm.
 * This concept is also similar to the Symbiotes, a race of amorphous extraterrestrial parasites which appear in the Marvel Comics shared universe, the most famous of these are Venom, Carnage, Toxin and Anti-Venom. The Symbiotes envelop their hosts like costumes, creating a parasitic bond through which the host's mind can be influenced.
 * It is revealed in Episode 23, that if either a Life Fiber infused being or a Life Fiber article of clothing gets its both sides cut by a "Anti-Life Fiber" Weapon, it can prevent its regeneration effect.