Oak Galls

Couldn’t work out what sort of acorns these were. They aren’t. They are Oak Galls.

“Oak galls are abnormal plant growths found on foliage and twigs that are produced by small oak gall wasps. Shapes of galls vary from spherical to urn-shaped to star-shaped to fuzzy. Inside the galls are the eggs and larvae of the insects.”
Well I didn’t know that!!!