I remember when I was a kid my folks drove to my grandpa's house in the South Bronx for a visit. On the way, a few blocks from the house we got a flat. later that evening we pulled of the punctured tire, put on the spare and my uncle pulled the object from the tire that punctured it. In his hand he held a jagged edged 4 inch piece of bone and announced, "you got a bone punctured your tire". Now that was the weirdest flat I ever remember getting. To this date I still wonder if it was a piece of human bone. Anyone who was familiar with the South Bronx in those days understands, it could very possibly have been a piece of human bone.