canister shot

This "ferrous sphere" was dug up by a homeowner here in East Tennessee, who lives within rock-throwing distance of a small Union Civil War fort. I've spent a day in her yard and have not found anything conclusively of Civil War vintage, but it should be there under the layer of big nails...

Dug this up yesterday at a civil war spot we go to frequently and was excited as it was the first piece of artillery I've found so far. I believe it's too small to be a cannonball but too large to be canister shot which leads me to believe it could be grapeshot but I'm not well informed on...

I've been working with the local military park and the regional archeologists. We've been out all week detecting their hiking trails. I even got to dig my first big chunk of exploded cannonball. Fun stuff. Anyway on to the topic at hand. At one of the places I've been detecting the property...