Thalassabysus

Planetary Data
An endless expanse of sea is the only sighting you could get from the surface, deep below, the seafloor rests very long beneath, to the point where most species wouldn’t withstand the atmospheric pressure in the highest peak of this planet, however, because of how deep below the floor is, you wouldn't find much life unless you went all the way to the abyss. The lack of life close to the surface allows a deeper insight into the water, revealing from space, for the naked eye an enormous coral reef cutting across the planet.

The sunlight doesn't reach most of the ground however, and because of this most of the life in Thalassabysus has adapted to total darkness. Water is the nest for all kind of life, and Thalassabysus is no exception, fish, invertebrates, crustaceans, algae and even mammals coexist in the depths, there is however, one dominant species, both in strength and intelligence.

Inhabitants
It’s only in the deepest abyss where we find the dominant species and recognized inhabitants of Thalassabysus, gargantuan partially transparent creatures whose only limbs thick enough to be visible for the naked eye are four legs and an ominous pincer for head. They have a hundred other limbs, but they are too thin to be visible, their heads could sever steel in half, despite how frightening that is, the pincers are only used for self defense as opposed to a tool for hunting, algae is much easier to find and consume contrary to fleeing prey, thus reducing the usage of energy they would otherwise need in such a violent environment.

Another quirk of the main inhabitants, it’s the surprising ability to ignore any changes in the atmospheric pressure, being able to walk to the peaks of the planet without much hassle.

Reaching a Thalassaluge is a daunting task, however, few explorations have revealed that not only they are sentient, intelligent, and willing to speak, but that they also have the resources and knowledge to flee to outer space, though, as you can imagine, it’s as hard for them to leave as it is for the average alien to get in.