https://hackaday.com/2021/04/22/the-fascinating-world-of-fasciation/

Looks like a case of fasciation!

Fasciation has many causes both internal and external. Internally, it happens because of a hormonal imbalance in the growth cells, a bacterial or viral infection, or a random genetic mutation. There are also environmental causes, like chemical exposure, cold and frost exposure, or fungi, mite, and insect attacks.