Monkey Brains Mystery

I was taking a walk at the park this morning when I came across this interesting fruit scattered about on the ground. to me, they look rather like brains. I had seen this over at the farm store sold as "Hedge Apple" and reputed to keep spiders and fleas out of your house. It has no odor and I doubt it could keep anything away.

On further inspection I discovered that it doesn't come from a shrub which I thought it would since it was called 'Hedge Apple' but that it comes from a fairly tall tree with orange stringy bark and simple leaves.
Looking in my tree book when I got home, I identified this as Osage-Orange. Mystery solved. I had never seen these before.

More pictures from my walk here: http://tiredsoles.blogspot.com/2007/11/morning-walk-fall-in-full-force.html