|The 60lb bomb went through a rubble-sorting machine twice but had no detonator|
A World War II bomb passed through a rubble sorter before it was discovered at a Norfolk quarry, managers said.
A bomb disposal team has carried out a controlled explosion on the device, an armour-piercing rocket with no detonator, police said.
It was found at Folkes Plant and Aggregate's site at Burgh Castle near Great Yarmouth, on Monday.
The device was brought to the quarry in rubble and went through the sorting machine twice, the quarry manager said.
A bomb disposal team from RAF Wittering in Cambridgeshire detonated the 60lb (27kg) bomb on Monday afternoon.
Manager Kevin Lee said he did not know where the bomb had originally come from.
"So many lorries come here that unless we saw it being unloaded there is no way we would know where it came from," he said.
"It had no fins or nose cone and these may have come off in the sorting machine.
"But the bomb disposal expert said it was safe as there was no detonator but it certainly made a loud noise when it exploded.
"He did not want to take it off the site so that was why the controlled explosion was carried out here."