It grows as feathered crusts and tufts on the face of the ice, a finger’s length at most, in branching fronds like the frost on a winter window, white with a faint grey-blue cast. Close up the fronds are slightly thicker and softer than true frost, and under a breath they do not melt. Broad growths run in streaks down frozen waterfalls and fan out across the lee faces of the ice spires. It is brittle and snaps with a tiny, clear sound in the cold air, and it has no smell, as nothing on the plane has.

It holds the ice faces of the plane wherever the wind does not scour them bare: the lee of spires and ridges, the sides of crevasses, the frozen cascades. It is thin and scattered everywhere, like all life on the Frost-Bound, and never thick enough to colour a slope.

It grows almost without moving. Like everything the plane’s cold catches, it is preserved rather than spent, and a frond grazed away grows back so slowly that a grazer must range widely to feed.

It spreads by tiny flakes carried on the wind and lodged in cracks of the ice, and a crust lives as long as the ice it grows on. Nothing on the plane rots, and a frond broken off lies on the snow unchanged until something eats it.

To the Stillhares it is all their food, and through them it feeds the Hoar Owls and the Frost-Born who snare the hares. The Frost-Born chew a little themselves in hard times; it is bitter and gives almost nothing. It is harmless.

Travellers take it for frost and only learn otherwise when a hare is seen eating it, and many go home believing that the Stillhares eat frost. Some say the lichen is frost that has been alive since before the plane went cold, and that a piece carried home would melt into water that remembers; brought to the Material Plane it wilts and dies within the day. The Frost-Born treat it with the same care as anything else that keeps them alive, and do not scrape a face bare.