This artifact was found on the planet Xi buried over 300 ft in solid rock. Xi is an irradiated, airless, and metal poor chucnk of rock. It formed around star that was either one of the 2nd or 3rd generations of stars to have ever existed. As such it was incredibly metal poor, as was the entire universe at that time, meaning this concentration of metal would have taken the efforts of an entire interstellar empire to amass this much.
Even more intriguing, this enormous chunk of Lead 208, Radium 224, and Radon 220 had to have decayed from Thorium 232, making it a 20 billion year old ojbject in a 15 billion year old universe.
Finally, faded undecipherable script is scrawled over ever square inch of this block.