We saw these fruit for sale at a great amazingly well-stocked deli. They are called Hedge Balls and are the fruit of the Osage-orange tree. The strangest fruit we have ever seen. We were tempted to buy one to try but never got around to it. When I googled them later I found that they are unpalatable (even to birds and animals) and are only used to repel insects by cutting them in half and leaving them around the house.
I wonder whatever possessed the store to sell them in the fruit section. I don't know what would have happened if we had tried to eat one, but I can't imagine it would have been pleasant. Even handling the fruit is known to irritate the skin. Fortunately Vyv had no reaction after posing for the above photo.