Fuzz Ball Mystery Solved

During a bout of insomnia, I was able to find the answer to my oak tree fuzz ball question. The puffy thing in question is called a gall. It seems there are many kinds of galls, some of them caused by insects, but this particular kind is apparently harmless and quite common on white oak trees. So, for all you folks for whom my puff balls have caused worry and insomnia, it's okay -- you may sleep now, for the mystery is solved.