Thanx, John, I'll try that. I've checked for seams and don't see any.It's fairly pitted, but I assume that is probably from being buried. It does seem remarkably round, but having visited the Alamo, San Jacinto, and other historic sites with cannons I don't recall seeing any with a bore this big (4.5 in.). I'm even more curious now -- How were balls made that long ago without a mold? I've also thought this could be ship's ballast, but the location seems to far from the gulf for anyone to be carrying something that heavy around for no really good reason. I had also thought maybe it was part of a ball and chain, but the only imperfections on the surface are the pitting. I'll try and get a photo to post.