Civil War field artillery shot identification?

Hi all! Been gone for ages on here, but I have a new question. I’ve had this Civil War cannon shot in the family for a very long time, since at least the early 1940's-50's. Sorry, born in 1958 so that's the best I can give you! We did have 2 Civil War swords until my mother sold them at a yard sale in the late 60's; one was plain, probably an enlisted man's sword, the other with a more ornate hand-guard, more likely for an officer. This shot is an odd shape, and weight, I can’t find anything to really match it. Never really thought too much about it until my son started asking questions about it. It weighs just shy of 5 lbs, is ~ 4 ¾” high and ~ 3” at the widest point. It is definitely solid. But it is flat on the bottom and it doesn’t appear that it was deliberately cut or flattened at a later date. Any ideas or suggestions on what this is as far as field artillery shot would be greatly appreciated!