It's a tube used in wiring old homes for electricity. The system was called "knob and tube" and the tubes carried a wire through framing boards to avoid contact with wood. The knobs held wires attached to surface of framing. It was a two wire, ungrounded setup that was popular from the late 19th Century until the 1930s.ORIGINAL: adshepard
Now a bit of help is appreciated. I'm not sure what this thing is. It's made of clay, about 4" long, it's hollow like a straw and has the letter "C" or "G", not sure on it's "lip". My guess is that it is a cigarette holder but that's just a guess. I've ignored these on previous dives thinking they were just junk but decided to bring one up and clean it to see what it might be. So what is it?
Thanks,
Alan