Strange Incident

[Mike HSV]

Driving home tonight had a strange noise from under the bonnet, was doing about 60mph, accelerating quite hard and it sounded like the car threw a belt, with whatever it was then travelling under the car knocking a few times as it went. I instantly pushed the clutch and hit the brake and had a look behind me, nothing obvious in the road but it was busy so I couldnt stop and have a look. I tested everything out, power steering, air con etc, all fine and when I got home had a good look under the bonnet and around the car, nothing!!!
Cant for the life of me figure out what it was, anyone offer any advice?? There was nothing in the road in front of me and whatever it was definately bounce around under the bonnet before it went under the car.
Help!!!!

Mike

[Bignige]

Could have been a bird?