My grandma's QH had a hard plastic apple shaped ball on a rope that he positively mangled (along with several buckets, a tube steel hayrack, and a few boards in his stall) over a couple of years. My sister's QH has a legit Jolly Ball hanging in his stall, mainly as a marker to keep him from pooping in his water (butt hits ball, doesn't come close enough for precision aim, lol), but he gives it a smack every now and again. My first horse was afraid of one, he just stood in his stall quivering. I might get one for Scout before winter. He's curious, playful, and absolutely fearless, I think he'll enjoy one, especially during the time he's "snowed in."