a fungus??????

a fungus??????

Observation - a fungus?????? - UK and Ireland. Description: I saw this in Kew gardens on a magnolia tree. I have never seen anything like it and wonder if it is a fungus, or if not, is it a plant disease?

I saw this in Kew gardens on a magnolia tree. I have never seen anything like it and wonder if it is a fungus, or if not, is it a plant disease?