Ancient Skeleton

This skeleton belonging to a presumably extinct Leviathan Class Organism is found outside the Lost River Laboratory Cache surrounded by scanners and cables. The skeleton is the only one known to exist and is approximately one million years old. It appears to be some sort of huge, carnivorous life form. The skeleton is composed of many bone plates. Running parallel on down either side of the skeleton are twelve large holes, the purpose of which is unknown. It has six eye sockets and many sharp teeth, each tooth being larger than the Player. This skeleton is large enough that the player can swim through the gaps left by its missing teeth.

The Precursor Race had discovered these remains, and set up a Laboratory near it for the purpose of studying the skeleton. This is evidenced by multiple Precursor lamp-like objects surrounding it.

In Life
It is near impossible to imagine what this creature looked like in life, as it is unknown how much of the skeleton is visible to us, and even how the creature moved. Despite being armored, this creature appears to have originated from a completely different group of animals than the other known creatures descending from an armored ancestor, these being the Research Specimen Theta, Boneshark, Sand Shark, Biter, Blighter and Rockgrub, having evolved armor convergently.

The skeletal features of the creature support a distinct origin, as unlike Research Specimen Theta - and presumably the other living armored creatures - which has a shell that is visibly separate from its spine and ribs, the Ancient Skeleton's shell appears to be derived from extensions of the spine and ribs themselves, the outline of these bones being visible from within the skeleton. This makes the Ancient Skeleton's shell more similar in design to that of a tortoise or turtle, where the shell is formed by the spine and ribs. As opposed to the other armored creatures which possess a more armadillo-like set of armor, being derived from hard plates on the skin.

Other unique features of the creature include its six eye sockets, and the strange holes running all the way down the body, both traits known only from this species.

Trivia

 * The Ancient Skeleton was once named Ancient Skull. It was named this up until a livestream in which it was pointed out to narrative designer Tom Jubert that the incorrectly designated "skull" had a spine and ribs within it, so was clearly not just a skull, but also the body.