Yukimarimo are balls of fine frost formed at low temperatures, between -50C (-59F) and -58C (-72F).
This phenomenon was first noted in Antarctica in 1995. The balls are formed by electrostatic attraction between ice crystals. Yukimarimo are very light and very similar to cotton. They behave a bit like tumbleweed in deserts.
Picture by Heather Moe, NOAA Corps