I recently unearthed this glass object. My first thought was that it was one of those bottles with the indented bottom, but the "bulge" is solid glass. Next it looked like it could be an insulator, but there are no threads (oh wait...I think I just figured out someone meant in his posting for threadless insulators...). But even if it is a threadless sort, what about the lip at the bottom and where is the wire groove?
Is this even an insulator or am I completely off base?