Technetium

Technetium is a substance of some sort. It is apparently desirable to Autobots, as Optimus Prime, Meltdown, and Showdown all searched for it at some point.

Fiction

Transformers: Universe

At some point, Optimus Prime, Meltdown, and Showdown were searching for technetium. General Freeman warned them that their efforts were attracting too much attention, and stated that the desert contained nothing of value to the Autobots.

Notes

• In real life, technetium is the 43rd element, and is the lightest element to have no stable isotopes; basically, it's always radioactive. Why the Autobots want it is not entirely clear; although it has applications, its radioactivity kind of puts a damper on that.