Oak Sower Gall
Q: We found a fuzzy, gall-like thing on an oak at Cochran Mill Nature Center. It was white with brownish-red spots. Upon breaking it open, it has seeds inside and appears to have pierced the bark of the tree branch that it was surrounding. Any ideas?
A: You found an oak sower gall. It formed in reaction to a tiny wasp laying her eggs on the bark of the oak twig. Tree tissue grew around the eggs, protecting them from predators. The seed-like things are actually capsules where the wasps develop.
You can put the gall in a glass jar and wait for the wasps to hatch in a week or so. Since they are harmless to both humans and trees, simply release them when your curiosity is satisfied.