"Frost flowers" are "a strange phenomenon where frost grows from imperfections in the surface ice amid extreme sub-zero temperatures nearing -22C or -7.6F, forming spiky structures that have been found to house microorganisms. In fact, the bacteria found in the frost flowers is much more dense than in the frozen water below it, meaning each flower is essentially a temporary ecosystem, not unlike a coral reef."
The cold, moist air above the open cracks becomes saturated and frost begins to form wherever an imperfection can be found on the ice surface. From these nucleation points the flower-like frost structures grow vertically, quickly rising to centimeters in height. The hollow tendrils of these “frost flowers” begin to wick moisture from the ice surface, incorporating salt, marine bacteria, and other substances as they grow.More details (and additional photos) at Colossal, via allhomosapienswelcome. Unlike the land-based "frost flowers" I used to see when I lived in rural Kentucky, these Arctic ones are truly made from frost, not from extruded ice.