Some mountain snow turns pink from algae that thrive in the cold

In summer, patches of alpine and polar snow can turn a deep watermelon-pink, colored by blooms of the cold-loving algae Chlamydomonas nivalis. The algae produce a red carotenoid pigment that shields them from intense UV light at high altitude — and that same pigment absorbs more heat, subtly speeding up the snow's own melting.

— Ronald W. Hoham, Snow Algae: Snow Albedo Changes, Growth, and Ecological Functions — research on Chlamydomonas nivalis blooms