Gall wasp balls

I found this little cluster in the driveway under an oak tree and, after a quick internet search, learned that they are balls (or galls) that would have held gall wasp larvae. The holes in the sides of the balls seem to be where a bird broke in to have little waspy snacks. For more on these parasitic wasps, I direct you to the Left Coast Naturalist blog: http://leftcoastnatty.blogspot.com/2010/09/oak-gall-wasps-cynipids.html I may rephotograph/reprocess at some point to achieve a better result.