Control crystal

Control crystals are power sources from the Generation 1 continuity family.

Control crystals are good for about everything. They can power spaceships, cure or prevent (organic) illness, store minds and grant Transformers near invincible strength. And that's just the known list of of uses. So of course, they are ridiculously hard to come by.

Fiction

The Transformers cartoon

The Heart of Cybertron would seem to be a control crystal. Microbots

Marvel UK Comics continuity

Snarl's case of Corrodia Gravis had gotten to an advanced stage and still there was no cure. The only thing the Dinobots could think of to save their teammate was to get a control crystal and store Snarl's brainwaves in it while they'd get him a new body. The only control crystal they knew to still exist was the one that had powered the shuttle that had brought them to the Savage Land long ago. Since they had left the shuttle there, they returned to the Savage Land. However, the crystal was missing from the shuttle. Homing in on the control crystal's energy aura, the Dinobots travelled through the Savage Land to fetch the thing, encountering many sick or dead dinosaurs on the way. The control crystal turned out to be in the possession of a human, Professor Embrey, who begged the Dinobots not to take the crystal as it was the only thing preventing a group of dinosaurs he was looking after from getting sick and dying too. Swoop suggested that they'd use the crystal to transfer Snarl's mind into a stegosaur and that Embrey would look after him in return for keeping the crystal. That suggestion was agreed to. Destiny of the Dinobots!