However, since both the Metroid and the Castlevania series have been often compared to since the release Castlevania: Symphony of the Night, it is more likely that Nominon's origins are linked to Phantoon, an enemy boss which made its debut in Super Metroid in 1994.
Nominons are a small, tentacled spirits that float around their prey waiting for a perfect opportunity to strike. The monster will quickly lunge and attach to their heads, paralyzing them, and then proceed to use its tentacles to suck up their souls. They are usually encountered when there are other enemies around, and use these distractions to their advantage.
They are remarkably weak, however, and a single strike from most weapons is usually enough to put them down, making fighting them more a matter of precision than of strategy.