An Army bomb disposal team had to be called in after a fishing trawler landed more than its crew expected.
The boat Intrepid was fishing off Rosslare, Co Wexford, when it hauled in a suspected old artillery shell in its nets.
The "catch" was landed at Kilmore Quay in Co Wexford and the port's west pier was sealed off by gardai to await the arrival of an Army explosive ordnance disposal team from Cork.
Officers later identified the device as an antique six-inch artillery shell dating from the 1800s.
It was likely to be from a rifle cannon and was badly corroded, the army disposal team said.
It was rendered safe and a spokesman said it was unlikely to have contained any explosive.