Believe it or not, making ice is more complicated than just making water really cold. One thing that helps is bacteria. Yes, bacteria! In this captivatingly magic video, it takes just a second for Pseudomonas syringae to turn a whole jar of water into ice.
How does it work? It's the same principle behind how snow forms in the atmosphere. An ice crystal needs to form around a nucleus, which can be a bit of dust, soot, pollen, or, as we've seen, bacteria. Pure water doesn't have to crystallize into ice until it's as cold as 55 F below zero. In the demo here, the water has been supercooled to about 21 F, but it only freezes over after the P. syringae is added.
Maggie Koerth-Baker, who first spotted the video for Boing Boing, explains where P. syringae's cold superpower comes from.
We humans might think ourselves clever using bacteria proteins to make artificial snow for ski resorts, but the microbes have been way ahead of us.