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.

The Original Life Fiber was supposedly destroyed when Ryūko and the S.S Naked Sun cut through its core in Episode 23.

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. Their evolutionary history is unknown, but they are unique creatures that are vastly different from any form of life on Earth.

Life Fibers are multi-cellular microorganisms whose bodies grow in long thin strands, which radiate bright red energy. These strands are very durable, being stronger than most materials found on Earth. 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. In order to maximize the longevity of a host, they cover their host's body and bind to their peripheal nervous system instead of inhabiting their internal organs.

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. All Life Fibers seem to be incapable of talking to their hosts. Ryuko, on the other hand, has the exception where her Kamui, Senketsu, can speak telepathically. This is due in part by Isshin Matoi inbuing Ryuko's gene's into the fibers. Life Fibers are also capable of manifesting new abilities in response to certain stimuli (usually life-threatening situations). Their ability to rapidly evolve is one reason why they are considered dangerous.

Life Fibers reproduce across the galaxy through a series of steps. After finding a planet with intelligent life suitable for their purposes, they begin subtly manipulating the evolution of a select species, creating a race that will become the dominant species on the planet. Once the selected species has dispersed across the planet and reached a certain stage of evolution, the Life Fibers will begin taking control of that species on the planet. When enough members of the species have been parasitized by Life Fibers, the aliens will take control of their hosts and rise into the stratosphere, creating a massive "cocoon" of Life Fibers that envelops the entire planet. In this form, the Life Fibers consume the planet's thermal energy to create new Life Fiber seeds. Once enough seeds have been created, the Life Fibers will cause the planet to explode, scattering the new generation of Life Fibers all across the cosmos in a kind of galactic diaspora.

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 backfired causing the student to become a berserking, muscular, hulk like monster. Hōka Inumuta was the only one able to restrain him. This demonstrates that only certain people have 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.

Most Life Fiber garments have one Banshi, but Senketsu was shown to have multiple threads that must all be removed to destroy him. It is unclear if this is a natural trait of Kamui, a unique element of Isshin Matoi's design, or a consequence of Senketsu's ability to absorb the Life Fibers of destroyed Goku Uniforms (which likely includes their Banshi).

COVERS
COVERS (カバーズ) are Life Fiber entities that are responsible for the dissemination of Life Fibers throughout the world. The name "Revocs" is an anagram of their name.

COVERS can roughly be separated into two groups: cloth-form COVERS and human-form COVERS. Cloth-form COVERS appear as white business suits with a red bowtie that need to stay in contact with the Original Life Fiber in order to stay active - usually by one or two Life Fibers that connect them to their source. When a cloth-form COVER absorbs a human being as an energy source, it becomes a human-form COVER that can operate autonomously. In this form, the COVERS gain a more substantial, muscular appearance, with their "bowtie" enlarging into eye-like growths and a necktie-shaped hole appearing in their chests that bears the emaciated face of its absorbee.

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 Fibers infused being or a Life Fibers article of clothing gets its both sides cut by a "Anti-Life Fibers" Weapon, it can prevent its regeneration effect.