Ice on branch

Ice on branch

Observation - Ice on branch. Description: Ice crystals formed on a piece of wood. Temperature recorded on my weather station at the time was -0.8C, the lowest overnight. These crystals were much larger than any of the rime nearby. Pocket knife is 72mm for scale. I have seen this on other occ

Ice crystals formed on a piece of wood. Temperature recorded on my weather station at the time was -0.8C, the lowest overnight. These crystals were much larger than any of the rime nearby. Pocket knife is 72mm for scale.

I have seen this on other occasions and I believe it may be caused by a fungus in the wood. Can anyone tell me if this idea is right and, if so, what purpose it serves the fungus?