This is an exciting item if you are interested in old shipwrecks.
I do have a minor quibble/query. There is a reference therein to live cannonballs .
I thought cannonballs were just inert lumps of iron which smashed the wooden hulls of enemy ships after being fired from a live cannon. The ball itself not being live. And being pretty solid, you couldn't tell whether one had been fired or not.
a cannonologist might be able to tell if one had been fired by feeling its bumps or something, though if it was lying on the bottom of the sea that would be a fairly good hint anyway. But yes, new or used, they're all dead.