The Baghdad Battery refers to 3 ceramic pots all containing a tube of one metal and rod of another metal. It contains all the elements, minus the acidic liquid, and structure to make a working battery.
The anomalous problem is that these “batteries” are dated circa 250BC.
(Image ownership https://commons.wikimedia.org/wiki/File:Ironie_pile_Bagdad.jpg)
Some have proposed that perhaps these “batteries” were indeed batteries used in ancient electroplating, but that calls into question ancient knowledge, the discoveries of electricity, battery technology, aspects of chemistry, and the discovery of electroplating.