Ea
“"If you are resolved to know it, we will disclose to you the truth we discovered. The truth of the universe."
The Ea, whose lingering remnants can be found in Ostrakon Tria, achieved the very pinnacle of technological advancement and transcended their physical forms to attain a form of immortality-only to lose all ambition upon concluding that the universe was doomed to a cold death. Whether those who were converted to dynamis felt this despair more profoundly than they did before their previous demise cannot be known, but Coph-coodg was deep in its grasp by the time the Scions encountered them. Nevertheless, their insistence that life was an exercise in futility was no match for Y'shtola's curiosity and Urianger's determination, and together were the pair able to illuminate a way forward.
— Encyclopaedia Eorzea Volume III, p. 185
The Ea are an immortal, incorporeal race first encountered at Abode of the Ea in Ultima Thule. They claim to have originally been physical, organic beings similar to the ones found on Hydaelyn. As a result of their scientific successes, the Ea were able to solve all disease, war, and scarcity in their society. However, this complete understanding of reality led them to a state of severe nihilism after their discovery of the inevitable heat death of the universe. This realization was the first to send Meteion on her downward spiral to become The Endsinger. One can only presume that some of the planetary remnants at Ultima Thule belong to the Ea homeworld.