The Dropa stones, otherwise known as the Dzopa stones, Dropas stones or Drop-ka stones, are said by some ufologists and pseudoarchaeologists to be a series of at least 716 circular stone discs, dating back 12,000 years, on which tiny hieroglyph-like markings may be found. Each disc is claimed to measure up to 1 foot (30 cm) in diameter and carry two grooves, originating from a hole in their center, in the form of a double spiral. The hieroglyph-like markings are said to be found in these grooves. There is no concrete evidence of the discs' existence. No record of any of these discs being stored in any museum in the world has ever been found, and they are believed to be a hoax.
With Wegerer's photos lacking concrete evidence of the hieroglyphs, they display similarity to Bi discs. Bi discs are round jade discs with holes in their centres. When buried in the earth, the minerals change them to be multi-colored. Bi discs have been dated from 3000 B.C.E. and were common in the Shaanxi Province. Some Bi discs are decorated with parallel grooves and other markings
More information on the Wikipedia page .