The Blue Magunesu, also known as a Magnite or Magnes, is a floating metallic creature, which moves as far away as possible from Link when he comes towards them. They will frequently flip around, turning into Red Magunesu, and in doing so shoot a small fireball at Link. They can be attracted/repelled by the Magnetic Gloves, but the best strategy is to wait until they try and flip (they are not able to move while doing so), and slash them twice quickly.
Sword - 2 hits
The only difference between the blue version and the red ones, is that the Magnetic Gloves will repel them when turned red, and attract them when turned blue.