From 2speccers2tools wiki

In the polar regions of Kamm, the Nostalgias were frankly starving. This caused them to seek more nutrients at sea, where there turned out to be a surprisingly large supply of food. So they started eating it. Specifically, the nutrient-rich and generally edible poop flora. This sparked the evolution of the nostalgitee, the largest pissfauna on Kamm at the time it evolved. It has replaced its ancestor within its range.

Nostalgitees have a mostly aquatic lifestyle, facilitating their diet of poop flora. They can usually be found in the water, using their short proboscis to vacuum up their prey. They can hold their breath for up to 30 minutes due to their greatly expanded left lung, only surfacing in order to get air. Their ability to swim is made possible by the cartilaginous fin that wraps horizontally around their lower half, and they are able to keep warm in the frigid water thanks to a thick layer of blubber under their skin. Like like the terran greenland shark, the nostalgitee also has urea present in its flesh, preventing its thinner parts from freezing and making it unappetizing to whatever predators it may have in the distant future.