It has been established in various media and in-game sources, in particular Metroid Fusion, that the Metroids' major weakness is cold temperatures; merely placing them in a sub-zero environment is enough to either make them sluggish or cause them physical harm.

The Metroids were genetically engineered by the Thoha Chozo to exterminate the X Parasites on SR388. The creatures had the ability to siphon the energy of a bioform, reducing it to a brittle husk.

Blue Hatches (Security Level 1) can be found throughout the Biologic Space Laboratories research station in Metroid Fusion. They are mostly in Sector 2 and are the blue colored doors. To open them, Samus must find the Level 1 Security Room, located in the top right corner of Sector 2.

She was raised on the mining colony K-2L, and when she was a child, the planet was raided by Space Pirates led by Ridley in an attack that killed her parents and destroyed the colony. The orphaned Samus was then found by a bird-like alien race known as the Chozo, who brought her to their home planet, Zebes.