Here's an interesting thing. While walking through the forest with Larry, we came upon a small, round thing that Larry picked up and wanted to show me. Below is the video of it. Larry refers to this round ball as an "oak gall," but I've found that at times they are also called "oak apples" as well. After doing some research though, I found there is a bit more to these oak galls than Larry may know, which is rare indeed.
After doing some research on these oak galls, I found there is a bit more to them than Larry described. It turns out that the "worm that gets in there" that Larry was referring to isn't a worm at all, but the larva of a wasp. In fact, it is the wasp larva that creates the oak gall in the first place.
When a wasp lays an egg at the center of a budding oak leaf, the egg hatches, and the larva's saliva causes the leaf itself to mutate and form the thin, protective ball that becomes the oak gall. Notice the white, dandelion looking material inside the oak gall when Larry broke it open? That is all created by the mutation of the leaf bud, and holds the larva in place right in the center of the ball. After that, the ball also provides a nice little protective housing for the wasp to grow. It's remarkable. Oak galls.