A Danish mystery coin.
I picked this up today on a whim out of a box of unsorted world coins. Granted it's well circulated which may account for some loss in dimensions and weight, but it certainly seems to be significantly deficient in every aspect of the issue's specifications. Diameter is only 17.6 mm, thickness is just 0.4 mm, and it comes in light at 1.00 gram. More troubling is that the last year the type was supposedly struck was 1785.