The Corruption is a perpetually-expanding mass of necrotic organic tissue that appears in the Dead Space series. This substance has been present at the site of every Necromorph outbreak in the series' history and seems to be a vector for the spread of the Necromorph contagion as well as a method of altering any environment into a habitat suitable for Necromorphs.
Background[]
At every site of Marker activity, a Marker's signal affects all necrotic organic matter within its vicinity as well as affecting the minds of living sentient beings. Humans affected by the Marker undergo symptoms of psychosis, becoming paranoid, experiencing hallucinations, and ultimately becoming extremely violent both to others and themselves. As Marker-touched individuals turn homicidal and/or suicidal, they create more dead organic tissue for the Marker to manipulate. While never witnessed firsthand, it seems that a Marker produces the Corruption by breaking down corpses into an organic sludge that spreads across the environment. This might explain why, during the Second Aegis VII Incident, numerous corpses disappeared from the colony's morgue with there being an Infector present.
The Corruption appears to be an amorphous mass of flesh that constantly grows and spreads wherever it is found. It gives off a distinct odour much like vomit and produces toxins that alter the local atmosphere, making the environment incapable of sustaining human life. Attempts to destroy the Corruption biomass are futile as it can regrow as fast as it is incinerated. Areas saturated with the Corruption are difficult to traverse and are normally crawling with Necromorphs.