Yellow goo is a viscous, yellow substance encountered in Metroid: Samus Returns. It is present on walls and ceilings throughout SR388 as an obstacle for Samus. If she is ascending a wall or ceiling with the Spider Ball, she will instantly slip off on contact; the same happens if she tries to Wall Jump off it. The yellow goo is often present in large cavernous rooms or in chambers where Metroids are battled, such as the room where Samus encounters the first Zeta Metroid. Samus will have to work around walls covered in yellow goo using the Space Jump, Spider Boost or Turbo Bomb, as there is no upgrade or method to circumvent goo-covered walls otherwise.
While there is no direct predecessor to yellow goo in the original Metroid II: Return of Samus, there are a number of obstacles that are deliberately placed to prevent ascension with the Spider Ball in certain areas. Typically, these obstacles are spikes, but unidentified corrosive plant-like objects in the vertical shafts of Phase 4 also serve this purpose. Unlike the harmless goo, these obstacles deal damage to the Morph Ball. The yellow liquid also harmlessly hinders the Spider Ball, although this property is not present in Samus Returns.
|Hazardous||Acid (Beta/Fake) • Acid Rain • Afloraltite • Dark Water • Fire • Fuel Gel • Lava (Fake/Scalding-hot) • Phazon • Purple liquid|
|Gases||Dark vapor • Industrial-grade pesticide • Meta-viprium gas • Nohadin gas • Noxious gasses • Poison gas • Talvania Gas|
|Destructible|| Barnacle-like material • Bendezium • Brinstone • Cordite • Denzium • Frigidite • Glass • Grobnite • Ice • Maldium • Meltable Metal • Metroid webs • 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 • Crystals • Dark Sentinel • Lift • Liftvine • Light • Minerals • Phazon • Red magma • Sentinel|
|Ore||Urthic • Phazon|
|Miscellaneous|| Invisible platform • Jovian steel • Liquid Resource • Liquid solution • Sand |
Vaccine "Metroid" • Waste • Water • Yellow goo • Yellow liquid