Please forgive my tardy response. Unfortunately your inquiry got buried in my list of questions.

Your strange looking growth is a gall. Galls are abnormal growths or swellings of plant tissue caused by an organism. Galls come in all shapes, sizes, colors and textures.  They are mostly cosmetic and do not significantly harm the tree. Galls are formed by tiny insects, typically a small wasp or mite, that feeds on the leaves or limbs of the tree. They create the odd-shaped growths to protect them while they are feeding. Here is some information on twig galls:

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/other/galls/gouty-horned-and-other-twig-galls

https://hortnews.extension.iastate.edu/2010/8-25/oakgalls.html
Galls on leaves typically fall off onto the ground at the end of the season, but twig galls like yours remain on the tree. There is no "cure" for these odd growths