I am not real sure on this, but we have plenty of experts here that can give you an answer. I like it though, but saying that I would rather here from the experts.
not an expert but it looks like if it was it would use a Bormann fuze, possibly a 6 pounder. where was it found (general area, dont need to give up your honey hole if it is)
Looks likely but we'll need a good measurement of the diameter and weight. As was mentioned, if you can see any evidence of threads where the hole is that would be good to know also. Roughly where you found it would be useful info too.
Yeah, I'd say that's a Parrot shell chunk. As to the ball, if it's a six pdr it should be very close to 3.56 inches in diameter and weigh just under 5 1/2 pounds. Because of rusting and there being no fuse (and probably no powder internally) the specs likely won't match published tables exactly but if it's real close I'd say you've got a winner. Cool finds !