Reading the Army’s official history of my Father’s WWII battalion, they once dug 18 mines out of a six by six foot plot of ground.
The Germans must have stacked them on top of each other.
UXB is no joke in Europe, a German backhoe operator was killed a couple of months ago by an unexploded bomb. If you read the story above, the Belgians are still decommissioning gas shells from WWI found a year or two ago.