Na última vez que fui no PNI peguei uns desses absurdos! alguns com uns 15 cm!
https://en.wikipedia.org/wiki/Needle_ice
Needle ice is a phenomenon that occurs when the temperature of the soil is above 0 °C (32 °F) and the surface temperature of the air is below 0 °C (32 °F). The subterranean liquid water is brought to the surface via capillary action, where it freezes and contributes to a growing needle-like ice column.
The ice needles are typically a few centimetres long. While growing, they may lift or push away small soil particles. On sloped surfaces, needle ice may be a factor contributing to soil creep.[1][2]
Alternate names for needle ice are "frost pillars" ("Säuleneis" in German), "frost column", "Kammeis" (a German term meaning "comb ice"), "Stängeleis" (another German term referring to the stem-like structures), "shimo bashira" (霜柱 the Japanese term for "ice needles"), or "pipkrake" (from Swedish pipa (tube) and krake (weak, fine), coined in 1907 by Henrik Hesselman).[3]
A similar phenomenon, "frost flowers", can occur on living or dead plants, especially on wood.