Why it evolved

The perpetual darkness from the pressure drives selection for enhanced low-light senses and potentially bioluminescence for communication or prey attraction. As the creature likely moves into deeper, potentially colder cave systems with less reliance on precise temperature regulation from the parent's expanded heat-exchange surfaces, these structures can be reduced, saving energy. The reduced reliance on the parent's 'warmer waters' and the shift to deeper, darker zones implies a reduced need for extensive heat exchange, potentially making it more susceptible to temperature fluctuations. Its diet remains herbivorous, grazing on Rime-Mat, but its zone might extend into cave systems where Rime-Mat still grows.