I recently purchased this from an old gentleman who was rennovating a house I did some work at. He said it was an old prison ball. He said the hook was used when they stored them and a seperate chain was used for the shackles. He had owned it for over 40 years and couldnt remember where he got it but was 100% sure of his story. It is the same as a 12 pound cannonball. Ive researched and come up empty. I did find something similar on ebay that said thought to be a windmill weight. Any Ideas?