One that covers

The one that covers is a parasitic organism that can physically enhance and transform the host.

History
The parasites were discovered by Code Talker upon researching the remains of The End after Operation Snake Eater in 1964, and later reviewing the records of The Pain, although he had theorized their existence as early as the 1930s. After studying the parasites and even allowing The End's parasite to assimilate with his own body, Code Talker had the parasites sealed away.

The parasites were later resurrected in 1975 through reverse evolution. They were uncovered and stolen by Skull Face. The parasites were used in the creation of the Parasite Unit and the return of Quiet to active service.

Other effects
Some hosts generated a pitch black gas that could sometimes sparkle blue. The parasite acted as the host's skin, to a variety of effects. A primary effect was providing camouflaging abilities to the point of invisibility, phasing layers of flesh in and out of the visible spectrum to the point where the muscular system was sometimes visible. The black gas appeared when the subject vanished into thin air with their powers. This vanishing ability also can make the host at least partially intangible, which allowed Quiet to phase her hand out of handcuffs. Other possible abilities included disguising as another military force, and reinforcing the skin to a kind of armor, the material of which can be shot from the skin into the ground to cause sharp spike like structures to burst from it as a means of attack. The armor and mist variants of the Skulls could even produce their sparkling black gas and make their victims zombie like infected that worked with them to achieve their goal. This meant that these variants could turn others into violent zombies like those infected with the normal variant. Inhuman mobility, strength and resilience are highly common amongst these kinds of subjects. In addition, weaponized subjects could float down while mid air and slow their falls, a possible side effect of their gas like transformation ability. In return, the host becomes a source of nourishment of some sort for the parasite.

The parasite could also replace lost organs of the host, as seen in Quiet's and Code Talker's replacement of their digestive systems to make them photosynthetic, as well as the modification of her respiratory system to be cutaneous (through the skin) rather than pulmonary (through the lungs). Quiet was also resuscitated near instantaneously by sunlight alone after being drowned. The End had similar abilities, causing him to rapidly heal in sunlight, have inhuman resilience, and survive exposure from lack of shelter as long as he was exposed to the sun, air and water. He, like Quiet. also possessed an inhuman resilience to gunfire, as bullets and injuries did not slow either of them down or inflict lasting damage unless such damage was continuously done before they could use direct sunlight to recover.

A host of the non lethal strain of the parasite can be identified if black blotch markings can form around the eyes due to emotion, as Quiet speaking Navajo to Code Talker caused such markings to briefly appear on his face. These markings also appeared on Quiet's face when she was insulted by Miller, while she revived from drowning, and sometimes when she was in direct combat.

Some parasites bestowed special abilities upon their hosts if compatible.
 * Expanding natural human lifespan to approximately one-hundred years
 * Replacing and replicating the processes of the organs of the digestive system.
 * Inhuman strength, speed, agility, resilience and durability
 * Storing synthetic materials inside of the skin, such as firearms or metallic archaea
 * Near-invisible camouflage by augmenting pigments in the skin and seemingly phasing the users tissues in and out of the visible spectrum.
 * Covering the skin in a black rock-like material as armor which can be projected into the ground to cause spike like structures to burst from it.
 * Limited telekinesis
 * Photosynthetic skin that allows a user to recover from trauma, damage or toxins in a matter of seconds while they are exposed to direct sunlight.
 * Dispersal of a mist to obscure sight
 * Releasing heterogeneous pheromones that attract and have complete control of hive insects.
 * Releasing high amounts of adrenaline to override pain.

Behind the scenes
The parasites are a major element in Metal Gear Solid V: The Phantom Pain.

In one of the cassette tapes, it is revealed that, in addition to The End's parasite, The Pain had parasites as well. The End's parasite would later be transferred into Code Talker.

"Mist Parasite Parasites extracted from Mist-type Skulls. They possess the ability to produce a dense mist. Required for developing and using parasite supply cartridges."

- Mist Parasite description in Metal Gear Solid V: The Phantom Pain

"Camo Parasite Parasites extracted from Camo-type Skulls. Required for developing and using supply cartridges."

- Camo Parasite description in Metal Gear Solid V: The Phantom Pain

"Armor Parasite Parasites extracted from Armor-type Skulls. They possess the ability to protect their host's body through calcification. Required for developing and using parasite supply cartridges."

- Armor Parasite description in Metal Gear Solid V: The Phantom Pain

Appearances

 * Metal Gear Solid V: The Phantom Pain