Possible cannon ball?:

[A. F Medic]

[Johnny Peppers]

I don't believe that is a cannon ball. The originals were typically very smooth unless pitted from ground action. That looks more like the ones the local foundry turned out about 50 years back, including the crude sprue and the raised mold line.
My son has all of mine, but I will try to pick up a couple and make pictures.
This is a fragment of a Confederate 12 pounder that used a wood and paper time fuse. The picture shows the smooth surface under the rust, and this piece lay in the ground for 130 years.

[Jim K]

Iron balls were fairly common in Victorian architecture, being used as bases for railings, to anchor chain fences and as decoration on or around buildings. and the ball mill was common in ore mining areas. (A ball mill was sort of like a large case tumbler, where iron balls were used to crush ore. Of course, the balls themselves eventually wore to nothing but when more modern crushers were invented, spare balls were scavenged for other uses.)

(The above has been processed by the National Double Meaning Association and pronounced free of giggles, titters and snide remarks concerning the writer's anatomy and possession or lack thereof of balls of iron or other substances.)

Jim