A British man digging in his back yard with a spade turned up a live World War II anti-tank grenade, police said.
Paul Davis, 32, thought the 8-inch-wide device was an old lawnmower part and took it in to his Exeter home, the Mail on Sunday reported.
A friend took a photo of him holding it.
Later, curious about the device, Davis checked the Internet, realized he had a grenade and called the police.
A Devon and Cornwall Police spokesman said police told a dozen residents to leave their houses before experts detonated the grenade.
Davis said the grenade wasn't buried that deep in the earth.
"I've asked around, and apparently the guy who used to live here years ago had an air raid shelter," Davies said.
"It must have been buried then. I'm glad I didn't hit it with my spade when I dug it up. It could have been kaboom."
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