A van driver had a lucky escape on the motorway in Gloucestershire when a ball-bearing - described by police as a two pound cannonball - smashed through his windscreen on the M5
Police say the ball-bearing left a two inch hole, and could have caused a fatal accident.
It is believed the object was thrown from a car or bridge, following the discovery of another ball-bearing on the hard shoulder.
The van driver was unhurt during the incident on Friday at 0730 BST between junction 9 and 10.
Police say they are treating this seriously and have appealed for witnesses.