Mindelheim (dpa / lby) – A young man on a treasure hunt discovered a grenade in a field in Swabia with his metal detector. The owner of the field had allowed the man on Sunday to search the field near Mindelheim (Unterallgäu district), the police said on Monday. The mortar shell was still intact and dated from World War II. The called ordnance service advised covering them with earth again until the blast on Monday.