Parasite X

The Parasite X is a parasite witnessed only in Metroid Fusion. Mysterious, intelligent, and self-propogating organisms, the X are first encountered on SR388 as Samus Aran is watching over a Biologic's Research team when the X parasite comes out of the carcas of a dead Hornoad. The X infests Samus Aran' central nervous system, and renders her unconcscious. Shortly after, Samus Aran must have various important parts of her Power Suit removed, some of them even surgically. After being infected, the X could not be removed from Samus Aran' central nervous system, and she was given a very small chance of survival. Then, in a turn of luck, the Galactic Federation found a cell culture from the last Infant Metroid and quickly injected it into Samus Aran. Luckily, the X were completely and quickly destroyed by the Infant Metroid's cells.