An impressive mint destruct.
A coin without the reverse (the side with the denomination), but only with the obverse and its concave negative print on the other side.
This is a minting error created by placing a new disc on a struck but unstamped coin and re-stamping it. It is aptly called a "brakteat" minting because of its one-sided nature. Referred to as "brockage" by American numismatists.
Very rare for communist period coins.