Joulion concept art.
A Joulion[1] is a small, hovering entity resembling a bloated seahorse that appears in the BOTTLE SHIP's Cryosphere in Metroid: Other M. They will generally float about without attacking, but will occasionally generate a globe of purple-black energy. If Samus is near the Joulion, it will use that energy to project a bolt of electricity directly into the ground and charge around attempting to shock its target for several seconds, or at extreme range simply fire the globe at her. The creatures are vulnerable to all weapons, and when killed will explode in a large burst of energy that will damage Samus if she is standing too close, or destroy other nearby Joulions.
Super Smash Bros. for Wii U trophy description
"These enemies from Metroid: Other M look a bit like electrified water fleas. They inflate as they take damage, eventually exploding. In Smash Bros., they show up in the Pyrosphere stage, and you can make them blow up by attacking them. Hit them with combos for an even deadlier blast!"
Trivia
A Joulion in Super Smash Bros. for Wii U.
Joulion trophy.
- The Joulion's ability to generate and manipulate intense electrical fields is similar to that of another Cryosphere bioweapon, the Kyratian. However, it is unknown if there is any connection between the species.
- "Joulion" may have been derived from the term Joule, a common measure of energy, and Ion, an electrically-charged atom (both pertaining to the creature's affinity for electricity).
- The Joulion is also the only non-boss enemy in the game that does not demonstrate the "standard" explosion animation upon death.
- It highly resembles a type of water flea called Daphnia. This is evidenced from the antennae-like "arms" shooting straight up out near its head and the presence of a completely transparent body. Furthermore, the Joulion's name could have been derived from a Daphnia's Japanese name, which is mijinko.
- Joulions are spawned as enemies on Pyrosphere in Super Smash Bros. for Wii U.
References
Japanese guide