Argus stone

The Argus Stone was an incredibly powerful artifact located on the world of Aridas, apparantly giving whoever wielded it the power to control the universe. Almost certainly an exageration, but nevertheless, it must have still possessed tremendous power to convey the impression, causing Terran, Zerg and Protoss forces to battle each other over it.

The ultimate fate of the Argus Stone is unknown.

Origins
The origins of the Argus Stone are even more nebulous than its functions. However, it is likely that its origins lie with either the Protoss or Xel'Naga. The Protoss Dark Templar possess a number of 'Argus-based' devices (eg. Argus Talisman) and may be linked to the stone. Alternatively, the Xel'Naga are known to create incredibly powerful stones (eg. the Khaydarin Crystals and creating an object with the Argus Stone's power may not have been beyond them.