Ice

Every winter, 'snow monsters' up to 5-6 meters tall appear on Japan's Tohoku mountains. Siberian winds carry moisture that becomes supercooled droplets, freezing instantly upon hitting trees and building up over weeks into towering ice formations called juhyo.

Hot water can freeze faster than cold — a phenomenon called the Mpemba effect. Known since Aristotle but still unexplained, it was named after Tanzanian student Erasto Mpemba, whose question physicist Denis Osborne took seriously enough to research together.