a white furry animal

This hair ice only shows up on wood that is infected with a fungus. Exidiopsis effusa The fungus makes very small holes in dead wood. When the wood is wet and the temperature falls just below freezing, the water is forced out of the wood by metabolic processes of the fungus and freezes when it comes to the surface. More water is squeezed out of the wood and also freezes and so the crystal grows.