I saw these deformed looking tennis balls (or are they deformed aliens?) once in Texas along the road and I promptly forgot about them until they showed up on the preserve about a month ago. Dan was curious enough to look up the strange looking ...well, at the time we were not sure. Anyway, he found out these green balls are fruits from the Osage-Orange tree a.k.a Hedge tree. The Hedge tree has very long and thick thorns. The tree was planted as a hedge because cattle would not go through them. If they were kept trim, they would not bare fruit.
We saw this squirrel moving around the fallen Osage-oranges. He finally found one he liked and picked it up.What a mouth full!
Well, I learned something new! :0)
More information about this fruit from IAStateEdu.