A history fan who was walking under Worthing Pier swiftly alerted police after he found what he recognised as a World War Two detonator.
Hotel worker and keen fisherman Stephen Wiltshire found the device while looking for fishing weights under the pier.
Stephen, 32, said: “I was never really expecting to find something like that.”
“It has most likely been buried for 80-odd years, I would have thought it would have washed away years ago.”
Stephen, who lives in Durrington, had enjoyed collecting memorabilia from the war as a teenager, so when he saw the detonator sticking out of the sand he knew what it was straight away.
He added: “They rigged up the pier to blow just in case the Germans invaded so they could not land troops on the pier. It’s really fascinating.”
He also found a rifle round a few paces away from the detonator.
Knowing that both objects could be live ordnance and potentially dangerous, Stephen handed them into Worthing Police Station on Monday night.
The bomb disposal unit arrived at the scene at 9.05pm and took the detonator away.