Jelectro



Jelectros are electric jellyfish that stay in one place underwater in Super Mario Bros. 3. They cannot be defeated by any means and will hurt Mario if touched. A large swarm in the middle of level 7-4 makes a hard time for swimming, especially since the screen moves automatically. Mario should try and swim slowly when surrounded by them.

Interestingly two enemies from Super Mario RPG: Legend of the Seven Stars (Muckle and Leuko) look extremely similar to Jelectro.