If you go down to the woods today for a winter walk, you could be in for a big surprise.
At first glance, it looks like candy floss has appeared on tree branches.
On closer inspection, you can see hundreds of individual strands of what looks like delicate white hair.
As soon as these are touched by human hand or winter sun, they melt away.
This strange phenomenon is called hair ice.
The crystals are formed on rotting wood on humid winter nights when the temperature is just below zero.
Scientists have discovered it is caused by a fungus which enables the ice to form thin hairs with a diameter of about 0.01mm.
Hair ice – also known as frost flowers – has been spotted in County Fermanagh in Castle Archdale, Florence Court, Castle Coole, Cladagh Glen and Big Dog Forest.
In County Tyrone, it has been pictured in Omagh and Knockmany, near Augher.
So if you’re heading out for some daily exercise, see if you can spot this rare phenomenon before it melts away.