I posted this to my Dad's Facebook page (he has more and older friends than me). My aunt said this, "I keep thinking this looks like a toy ball for horses that is to be tied to the walls of a stall. The one I have seen doesn't have an open center but maybe they are made differently. The open center could be used for treats to encourage exercise. I have seen small versions for dogs."
Didn't someone else say something about seeing a similar object in a monkey enclosure?
