What fused the mutated Takea-rays?

Hello again, Greg!
BS01, Fusions#Artificial_Fusions:
“Mutated combinations of Underwater Rays and Takea - The Barraki used these creatures.”
BS01, Rahi/Unnamed Rahi#Experiments/Mutations:
“Mutated Fusions of Takea and rays used by the Barraki.[CTM]”
(CTM = Command The Toa Mahri - The Final Challange)

These were depicted in the 2007 Playsets:

  • What caused these fusions? Were they fused before they got onto Aqua Magna, or did the Pit Mutagen fuse them?
  • Are the involved rays Rahi or SM Creatures? (We have only seen underwater rays that are creatures native to Aqua Magna)
  • When Mata Nui cured the Pit Mutagen, would he have undone the fusions?