I have an old, rare and super heavy coin. On its front there are two wolves holding a banner with a crown over it. In the banner is the year 1775. The only writing I can make out on the coin is this: MOHLTA. On its back is a wreath on the left and right and in the middle a backwards 3 with two lines going up and down through it. There is also a K and an M under the symbol and a crown above it. The coin is about the size of a US silver Dollar and may way even more than the US silver dollar. It is copper, I think. Any ideas on its worth?