It is defintely an explosive-type cannonball. I'm sure about that because its size (6.25" in diameter, plus a bit of rust-concretion) means it is a 32-pounder caliber cannonball. The fuze is a Boxer timefuze -- named for its inventor, Captain Boxer of the British Army. Because your cannonball's Boxer fuze is made of brass, it is a British-made one. (The US did manufacture some after the civil war ended (and even as late as 1897), but the US-made ones had a wooden body. No Boxer fuzes are known to have been used in the American Civil War. There is a record of a June 1864 Confederate purchase-order for some British-made ones, but none have ever been excavated at a civil war site. Logically, your Boxer-fuzed cannonball cannot be connected in any way to the Confederate June 1864 purchase-order, because Beaufort was captured by the yankees long before 1864.
At 16.9 pounds, your cannonball has lost some of its iron molecules due to Graphitization (which is a type of corrosion -- I discussed it in my reply-post in the "Just an iron question" thread here at the What-Is-It forum). It originally weighed about 23 pounds. But the spike in it is definitely a later addition to its body, because it could not be fired properly with the spike sticking out from it.
You might want to know, somebody else has found another Boxer-fuzed cannonball, which looks EXACTLY like your ball, so I think it must be from the same place you found yours at. That other Boxer cannonball was for sale on Ebay earlier this month.
