What's contained by my ceiling? Now and then I hear a commotion in my ceiling -...

Now and then I hear a commotion in my ceiling - resembling someone is in near rolling a cellophane ball or something. I thought it be my son rolling his chair on the floor surrounded by his room but now I'm within another room and hearing it and he's not home. It freaks the cat out when she hear it. What could it be?
Answers:    Could be a snake. They can go up a wall and into the Attic at my house.
I would suggest that you may enjoy rodents. Is it usually at night that you hear these sounds? Mice and rats are nocturnal animals. Good luck.