Scientists who study fungi say the discovery of how it can create hair ice — fine silky hairs of ice that bloom like cotton wool from rotting branches of certain trees — is just one more example of the strange and wonderful things of which fungi are capable.

The strange phenomenon forms when mycelium, the roots of a cold-tolerant fungus, helps ice grown in hair-like strands as thin as 0.0004 inches in diameter, strands that can hold their shape for hours as long as the temperature remains near freezing.

The rarity of hair ice and the fact it only exists for a few hours is why it took so long since it was first described in 1918 to understand how it forms, researchers say.

"Hair ice grows mostly during the night and melts again when the sun rises," said Gisela Preuß , a biologist at the Wiedtal-Gymnasium in Neustadt, Germany, who was part of the study published in Biogeosciences.

The fungus most involved in hair ice is a type known as Exidiopsis effuse, says study leader Christian Mätzler from the Institute of Applied Physics at the University of Bern in Switzerland.

It is central to a process known as ice segregation, in which supercooled water trapped in pores of a material is pulled toward already-formed ice and freezes, causing the frozen structure to continually grow, as seen in the video below.

Although fungi are found worldwide — mushrooms are what spring to mind for most people — most escape our notice or attention because of their small size and the fact that most are hidden from sight in soil on in dead organic matter, where they perform an essential function of nutrient recycling by helping decompose such matter.

Fungi are classified as their own kingdom, distinct from plants — although they often resemble them — animals or bacteria, and the study of fungi is known as mycology.

The fungi most familiar to people, mushrooms, have a long history as a food source, although there are a number of types that are extremely toxic, even fatal.

However, many other varieties of fungus have proven invaluable for other purposes, such as producing antibiotics and a number of useful drugs.

While understanding the role of fungus in creating hair ice may not have any immediate benefit for humans, it is yet another example of the kinds of ongoing wonders nature can present us with, the researchers say.

"I would like to let people realize that science can be unforgettably beautiful without any need for relevance for things that matter in human needs," Mätzler says.

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