An 18th century cannonball encased in coral was found inside a checked bag at Fort Lauderdale-Hollywood International Airport, according to the Transportation Security Administration.
TSA agents said a diver had found the old projectile near a shipwreck.
Because the cannonball was still considered explosive, the baggage area was evacuated as a bomb squad investigated.
TSA took possession of the cannonball so it could be safely destroyed.
Three flights were delayed, affecting about 290 passengers.