Mutantrum is a metamorph, sea-urchin themed monster brought in to lure Leo (one of the "chosen" beings allowed entrance into the cave where the Lights of Orion were believed to be concealed) into Furio's trap when he disguised himself as his brother, Mike. Unaware of the deception, Leo rescued Mutantrum, believing his brother had survived the fall on Mirinoi. As Mike, Mutantrum explained that they had to get ahold of the Lights of Orion before Scorpius or Furio did.