I'll try to sort the picture out in the next few days.
In the late 80s, we were digging a new test-pit and came across a cylindrical item that wasn't on the plans. The factory's been there since 1917 and so the plans are a bit iffy, but, nobody ever met the Germans that dropped the bombs to ask them how many there really was. Four went off, but that didn't meant there weren't five - or six. We were close to getting the bomb squad in when we discovered that it was an unknown sewer pipe.
Lucky we didn't get it blown up....