cast iron sink decoy

I bought this cast iron duck at a yard sale, it weighs about 20 pounds and has a hole in the tale it is solid cast iron, the people said it was a door stop, but I don't believe it is,I believe they painted it black, would love some information from someone if they know what the thing is, I believe it is a cast iron sink decoy. Has anyone ever seen this before, if so would love some information.