As Ventus travels between worlds, he is attacked by a mysterious Unversed. He fights it off, but the Metamorphosis flies towards the Grand Councilwoman's spaceship. Ventus trails after it and pursues it throughout the ship, meeting Experiment 626 along the way. Ventus eventually catches up to the Metamorphosis in the engine room, where it had been causing large amounts of damage, and teams up with Experiment 626 to defeat it.
The Metamorphosis is a large, jellyfish-like Unversed with pale, light blue skin. It has a sleek body with three large tentacles, each with arrowhead-shaped tips. Its lower body condenses into a twisted, black tail. The Unversed emblem adorns the front of its lower body, while its circular, black face is on the tip of its upper body. Its red eyes are set in a sorrowful expression.
In Kingdom Hearts Birth by Sleep Final Mix, The Metamorphosis now has white skin, which fades to black at its tentacles. The lining on its body is now purple, with turquoise diamonds on each tentacle. Its lower body and tail are also purple and fade to black.