Well done to those of you who correctly identified this amazing tree's seed pods. I think it's a fabulous name for a tree. One of the reasons I was so confused by this seed pod was that I found it on the ground nowhere near the tree itself. A child had possibly picked it up and carried it to another part of the garden. Anyway, a member of the gardening team took us to the tree, and below it were dozens of the things. I should think they'd give you a nasty bump on the head if they fell on you. So the moral of the story is, don't stand beneath a Maclura pomifera Osage Orange during the Autumn. But then I expect you knew that already!