Stumbled upon this weird, bumpy green ball under the trees. It looks like a brain and is sticky to touch. What is it?

10. Lookalikes: Other Fruits That Might Confuse You
While the Osage orange is distinctive, it can sometimes be confused with other fruits or nuts. One potential lookalike is the black walnut, which also has a rough, green exterior, but is generally smaller and releases a strong, pungent odor when opened.
Another possible source of confusion is the horse apple, a colloquial name sometimes erroneously applied to Osage oranges. However, true horse apples come from a different species altogether. When in doubt, observing the tree and its leaves can help confirm the identity of the fruit.
11. What To Do If You Find One in Your Yard or on a Walk
If you encounter an Osage orange in your yard or on a walk, consider leaving it in place to provide food for local wildlife. Alternatively, you can collect the fruits and use them as natural decorations, particularly in autumn displays.
For those interested in gardening, planting Osage orange seeds can result in a hardy, drought-resistant tree. However, be mindful of the tree’s size and thorny branches when selecting a planting location. Ultimately, the Osage orange is a fascinating piece of natural history worth appreciating, whether in the wild or as part of your landscape.