Krocuss are small, heavily-shielded molluscoids indigenous to the Torvus Bog of the planet Aether. They are chemotrophs, thriving on toxins that they extract from their surroundings through the use of toxin-absorbing gills. While they are pacifistic by nature, they unfortunately leave an acidic trail behind in their wake as they roam around in search of nourishment due to their natural digestive processes. Their armored plating is so densely compacted that only a few weapons are known to penetrate through their shell; as such the only convenient way to dispose of one is to fire into its gills as they are opened, exposing the fleshy insides.
- Metroid Prime 2: Echoes (First appearance)