some characters from an old series in the 2012 series! The underground mutants were ordinary people mutated by Shredder to search nderground for the turtles, though they were never able to find them. Shredder ordered the scientists in charge of the project to shut down thew project and destroy the creatures. The creatures broke free, killed the scientists, and made their escape. They were drawn to the Turtle's lair after Shredder's defeat when they saw Karai in the sewers, attacking her and the turtles. After finding out they were all on the same side, they all decided to stop fighting. Donatello tried to whip up some retromutagen for them, but was too injured. Michelangelo, even though Donnie told him not to, made the retromutagen and gave it to them. Due to Mikey's fooling around, when the doses were given tot he mutants, it not only turned them human again, but allowed them to change between human and mutant at will! Donnie was flabbergasted, to say the least. The underground mutants included more than just thewse three, but the others have gone midless, and endlessly prowl the Undercity. Quarry is the leader of the group, and the sole female member. she is smart and straightforward. In her mutant form, she has sharp claws, can scale rock, has super strength, and can spit acidt hat can liquify stone. Stonebiter is the muscle of the team. In his mutant form, he has super strength, tough, stonelike skin, the ability to bite though and eat stone to tunnel, and the ability to scale rock. Finally, Razorfist is the fighter of the team. In his mutant form, he has a scorpion's tail, sharp claws, super strength, and the ability to scale rock.