Cynipid Wasp Galls
These pine cone looking galls remind me of the egg cases from the movie Alien. They’re actually the insect gall of the cynipid wasp. A bug guy identified these for me saying “there are several hundred kinds of cynipid wasps that each make their own kind of gall on a particular kind of oak.” So there’s no telling which cynipid wasp these galls belong to. I only wish I had done what he suggested and collected the leaf. I could’ve then held on to them until they hatched and possibly had them identified.