Michelangelo and the Vortex crystal.
The Vortex crystal is an object used during the ninth and tenth seasons in the 1987 TV series. It has the ability to warp reality, such as merging dimensions.
Lord Dregg came into possession of this crystal in the episode "Doomquest", and planned to use it in his conquest of Earth. However, his plans were thwarted when Doomquest himself arrived to obtain the crystal, and it briefly fell into the hands of the Ninja Turtles. Donatello and Raphael discovered that it had the power to reverse their unstable mutations, but the crystal was soon taken by Draconus.
Doomquest began using it to merge New York with the Dark Dimension, but the Turtles and Carter succeeded in getting it away from him. With no other options, Leonardo destroyed the Vortex Crystal by throwing it into the side of Doomquest's ship. However, some small fragments of the crystal were left on a tool that had been used to pry it loose, which the Turtles used to cure their unstable mutations in the episodes "The Return of Dregg" and "The Beginning of the End". Dregg also duplicated the Vortex crystal using a small fragment he stole from the Turtles, which allowed the development of his Vortex Transporter.