Civil War collector killed by140 year old shell
When I lived back there, I'd see lots of civil war cannon projectiles for sale. Collectors would roam the old battlefields (only tiny portions of which were parks) with metal detectors. I read about one who had invented a remote controlled drill press, with water cooling of the bit and a closed circuit TV, so that he could drill into and deactivate them while staying a safe distance away. And gad, this was a 75-pounder.
UPDATE More on the issue, this time from the experts, including a picture and CAD images of the naval fuses. Some news stories suggest that he was grinding rust off the outside of the shell, but I can't see anyone trying that without deactivating it first; he must have known how spark-sensitive black powder is. Just from the size of it he would have known it was a naval shell (for land use, 6-12 pounders were standard, and a 32 pounder was heavy siege artillery), and I'd assume knew about naval fuses.
Hat tip to reader Bill Bailey....