What is watermelon snow and why is it best not to eat it?

Although the pink colouring helps the algae Chlamydomonas nivalis stay safe in the harsh sun, it also reduces the ability of the snow itself to reflect ultraviolet radiation. This causes the snow to melt faster, which can harm glaciers.

Chlamydomonas nivalis is a favourite food for many species, including rotifers, nematodes, ice worms and legworms. A person who tastes watermelon snow may suffer severe intestinal distress.