It is not so much a case of asking for their ball back, but the navy have rung the police to ask for their mine back.
A navy practice mine sparked a bomb scare on Ruakaka Beach near Whangarei this morning after a man saw what he said looked like an old sea mine in the surf.
The man called police about 9.30am saying he could see a large steel sphere with spikes sticking out rolling around in the surf.
Sent a photo of the "mine", the head of the navy's operational dive team, Lieutenant Commander Greg Camburn, said it was one of their training mines. They are not live.
They laid 12 practice mines in Tauranga Bay near Whangaroa on June 25 but then bad weather arrived.
When the dive team went back, they could only find 10 - a buoyant mine and a bottom-dwelling mine were gone.
In the following 16 days the buoyant mine has drifted 170 kilometres south - including crossing the tanker route into Marsden Point - until washing up at Ruakaka today.
"We are very happy to have it back," Camburn said.
"It is very necessary for us to use them for training and we try and make them look real."
He was pleased the civil authorities had reacted by clearing the area to check it out.
The bomb clearance squad had been asked to load it on to their pick-up and take it home to Devonport.
Earlier this year the navy led a multinational mine-clearance operation in the Hauraki Gulf. This included blowing up one of the dozens of New Zealand World War II mines now sunk off Tiritiri Matangi Island.
History is on the side of caution when it comes to mines in New Zealand waters.
In 1940 the German raider Orion laid 228 mines in the Hauraki Gulf and one claimed the liner Niagara on July 19, 1940 off Bream Head. No one was hurt, other than the ship's cat Aussie.
It was carrying more than eight tonnes of gold bars, part of a British payment to the United States for munitions. Most of it was recovered from 121 metres of water. Five gold bars reputedly remain.
A year later another Orion mine claimed the New Zealand minesweeper HMNZS Puriri.
Five of the crew, including the commander, were killed in the explosion, again off Bream Head.
Most of Orion's mines have now been accounted for with many of them sunk.