Sbugs are a species of Zebesian scavenger that lurk in the underground section of Crateria, inside the powerless Wrecked Ship, in the Kraid's Lair section and blue rock section of Brinstar before the Morph Ball is obtained and in the original Tourian escape shaft before the Eye alerts the Space Pirates. They are blue in the ruined Tourian part of Crateria and in Brinstar, but green in all other areas. They can also be seen feeding on a corpse that rather resembles a Federation Marine, just outside Kraid's room, pictured to the left. They are small in size, and flee as soon as anything larger, such as Samus, comes near them. The only location where the creatures will consistently reappear is at the site of the aforementioned corpse. Whether they are solely scavengers by nature or are simply taking the opportunity to eat a free meal, is unknown. Their fate after the destruction of the planet is also unknown.
Their name derives from the debug mode of Super Metroid, which refers to them as SBUG, possibly meaning "Small Bug". Whether this name is official or not is unknown, but no other name exists for the creature, official or otherwise. It is likely however that "Small Bug" is its true name, and "Sbug" is an anagram.