"Beta Acid" (as named in the Metroid Fusion code) is a highly corrosive blue-green liquid found in Mother Brain's chamber after Tourian is destroyed in Metroid: Zero Mission, replacing the lava that was there before. It is dangerous to step into even when Samus is wearing the Gravity Suit. This substance is not present in Super Metroid, which could suggest that it dried up or drained from the room.
Super Metroid did, however, have a red liquid possessing similar corrosive properties to Beta Acid; it ignored the damage reduction of the Gravity Suit, ultimately proving hazardous to any contact with Samus' Power Suit.
The same substance is also present aboard the Biologic Space Laboratories research station, in several corridors in the Tourian-like area of Sector 1, one of said areas being the room before Neo-Ridley's chamber. Like in Zero Mission, the substance's corrosive effects are harmful even to the Gravity Suit.
- Metroid Fusion: The Official Nintendo Player's Guide refers to the substance as "dangerous liquid" and "dangerous water". The former name was also used to refer to the acid that blocked off many caverns on SR388 in Metroid II: Return of Samus.
- This substance, possessing corrosive properties and a green color, may be yet another reference to the Alien film franchise, as the Aliens in the franchise have acidic green blood.
- The appearance of the liquid bears a striking similarity to waste found in Metroid Prime 3: Corruption. However, the waste is not harmful.
|Hazardous||Acid (Beta) • Acid Rain • Afloraltite • Dark Water • Fire • Fuel Gel • Lava (SR388) • Phazon|
|Gases||Dark vapor • Industrial-grade pesticide • Meta-viprium gas • Nohadin gas • Poison gas • Talvania Gas|
|Destructible|| Bendezium • Brinstone • Cordite • Denzium • Frigidite • Glass • Grobnite • Ice • Maldium • Meltable Metal • Radion • Sandstone • Talloric Alloy • Vegetation • Zebetite |
Kelbium and Zafrite
|Phazon||Red • Crystal • Black Crystal • Mass • Ore • Elite Nutrient Mix • Strain Vertigo • Phazite (Red) • Concentrated|
|Crystals||Ammolite/Witherite Shards • Black Phazon • Crystallized Fuel Gel • Dark Sentinel • Lift • Liftvine • Light • Phazon • Red magma • Sentinel|
|Ore||Urthic • Phazon|
|Miscellaneous||Invisible platform • Jovian steel • Liquid Resource • Sand • Vaccine "Metroid" • Waste • Water|