While at a local yard I noticed one guy that was turning in copper bolts with his other stuff. He didnt know what they were for or any history. I was curious cause they were pretty big. I dont have a pic but the shanks were bigger 1/2 at least and the heads were prolly 3/4 inch to 1 inch. They heads had a infinity symbol on them but that was the only marking. Just curious about what they could have been used for.