Could very well be an electric detonator. It looks almost like the kind we used in the mines in the 70's, but I don't know what the size of that thing Is?. Non-El's are whats mostly used today underground. Those things have a potential to just go off. Problem was that when they did go off for some unknown reason no witnesses were left to explained exactly what happened and why it went off before they left the shot area. A shot went off in the mine I worked at and blew two miners to bits. A guy I knew on the recovery clean up told me he picked up one miners rubber mine boot with his foot and ankle still in the boot.