The Baghdad Battery is a set of Isu batteries that generated power by harnessing energy released by the passage of time itself.
The Baghdad Battery, as it is called by the humans, is a set of three artifacts: a tube of metal, a rod of another metal, and what appears to be a ceramic pot. They are, in fact, components of an Isu battery which contained a synthetic, crystalline element akin to what is known to theoretical physicists as "Time Crystals". The analogy stems from the substance's ability to siphon energy generated from the passage of time itself, thereby allowing the overall device to produce unlimited—though minute—levels of power. While this was enough to power only a small light-emitting diode, it was a highly efficient means of producing light given that it could run perpetually.
Discovered by human archaeologists in Iraq, the function of the artifacts they called the Baghdad Battery baffled them for many decades. It was not until 2014 that researchers at Abstergo Industries were able to conclude that they were components of a battery that used time as a source of energy.