The larvae of the cynipid gall wasp Andricus corruptrix cause galls to form in the buds of Oak (Quercus species).  The asexual galls are in buds, and are hard and woody, with 1-5 smooth lobes, sometimes with tiny rosettes in the centre of the apex.

[Note: Sexual galls are formed in the buds of Turkey Oak, but are difficut to separate from the sexual galls of A kollari and A lignicola).

Photograph the gall on oak, and note the host species

oak trees

not known

See British Plant Galls (Redfern & Shirley, 2023)