Well, the history channel is on in the background (surprise!) and theres a show about pirates/blackbeard. They were showing a 'grenade' which they found in what may have been blackbeard's  ship. It was a hollow iron ball, filled with blackpowder, and plugged with wood and a fuse.
There description mentioned that it was "Thrown by hand or flung with a sling"

Anyone know more about this?

BK, I thought of you (now wouldn't that be embarrassing if you aren't the Blackbeard guy)