From the July 22, 2015, Guns.com.
U.S, Navy divers working in the muddy waters of the Savannah River pulled up the first os several cannons from the Confederate ironclad CSS Georgia's shipwreck.
Known as the "Lady's ironclad" as it was paid for largely by women's groups donations was under-powered and a primitive warship which never fired a shot in battle before being burned and sunk as Sherman's troops entered Savannah in Dec. 1864.
So far, divers from the Mobile Diving and Salvage Unit 2 and Explosive ordnance Disposal Technicians have cleared nearly 100 pieces of unexploded ordnance from the site.
The first barnacle-encrusted cannon was raised from the Georgia last week and turned over to the Naval History and Heritage Command for preservation.
There is a picture of the cannon with the article as well as video of it being raised. Very heavily coated with marine secretion.
No mention what kind of cannon it is, though. Likely a Brooke Rifle.