Hurricane Matthew put many lives in danger on its own thanks to heavy flooding.
But it also revealed relics from the Civil War. Cannonballs were found at Folly Beach near Charleston on Sunday afternoon. The first shots of the Civil War were fired at nearby Fort Sumter in 1861.
The cannonballs were not blown up immediately because high tides prevented officials from getting to them.
The cannonballs were detonated Monday afternoon, though some were sent to a nearby Navy base.
Sheriff's spokesman Maj. Eric Watson advised locals who came across the cannonballs to call authorities immediately, since the black powder in the cannonballs makes them unstable.
Here's the sheriff's full statement.
The Associated Press contributed to this report.