"Hair ice (also known as ice wool or frost beard) is a type of ice that forms on dead wood and takes the shape of fine, silky hair. It is somewhat uncommon, and has been reported mostly at latitudes between 45 and 55°N in broadleaf forests. In 2015, the fungus Exidiopsis effusa was identified as key to the formation of hair ice."

https://en.wikipedia.org/wiki/Hair_ice
https://en.wikipedia.org/wiki/Exidiopsis_effusa
paper: http://www.biogeosciences.net/12/4261/2015/bg-12-4261-2015-discussion.html