Marker discovery and worship
Over two million years ago, a technologically and socially advanced alien species inhabited the vast water covered planet of Tau Volantis. At some point in their history, they discovered an ancient artifact similar to the Black Marker discovered on Earth by Michael Altman. Like humanity's Unitologists, the aliens began worshiping the strange artifact as its promises of new, effective, limitless energy seemed to be the bright beacon of a shining future. The aliens built faux Markers across the planet's surface to generate more energy to power their civilization. However, the Markers would soon reveal their true intentions.
Tau Volantis First Convergence Event
Soon, a violent outbreak spread across the planet, killing and converting the majority of the population into horrific Necromorphs, all of them slaved to the Marker's will. Once the carnage had killed enough of the population to provide sufficient quantities of necrotic bio-mass, the Markers that were spread across the planet initiated a Convergence Event, with the collective mind of the infection attempting to assimilate the planet's dead and infected into a Brethren Moon that would continue spreading biological destruction across the galaxy.
The aliens were extremely resourceful, however, and were able to quickly construct a massive terraforming Machine to flash-freeze the planet, stopping the Convergence Event in its tracks and preventing the Brethren Moon from becoming whole and halting the spread of infection across the galaxy. However, their success came at the cost of their own extinction.
Two million years later, in the year 2311, the Sovereign Colonies Armed Forces discovered the planet and the remains of an alien specimen that they called Rosetta. After studying Rosetta, Dr. Earl Serrano discovered the truth and tried to complete the aliens' unfinished work, but in 2314, General Mahad received orders invoking a purge of all of the personnel, information, and assets on and in orbit of Tau Volantis before Serrano could get the alien Codex required to complete the process of the Machine.
200 years later, in 2514, an expedition led by Isaac Clarke rediscovered Rosetta and unlocked knowledge of the lost species and their technology, using it to fulfill the aims of Serrano and the aliens: Kill the Moon and stop the threat of the Markers forever. Despite their best efforts, however, the expedition was unable to prevent the remaining Brethren Moons from making their way to Earth to consume its population.
The Alien anatomy was described extensively by the studies and notes of Dr. Earl Serrano, collected from the data found within the frozen body of Rosetta, one of their kind and amongst calcified bodies found within the underground city that circled the terraforming Machine.
The aliens are mostly fish-like in nature with gills and collapsable fins which allowed Dr. Serrano to deduce that the planet had at one point not been covered in ice, but a vast ocean.
According to Serrano's research, the Aliens communicated with six holes within their skulls that let out harmonic noises with a similar cranial design as human nasal passages. He deduced, however that this was not their primary language form and this method was developed by the Aliens to allow a form of cross species communication. This pseudo-language that they developed was created to convey their information to creatures and beings that found their culture long after their extinction.
The creatures were described and shown as varying in size, some being small and about the same size of a human and others towering to the point of being as tall as a Nexus. The Alien Machine was riddled with calcified remains of the giants.
- The fact that the Nexus looks similar to the drawings Dr. Serrano has of the Aliens, as well as the fact that the Nexus is about the same size of one of the calcified alien skeletons found around the machine, suggests that the Nexus may be a Necromorph variant of the alien species.
- During the last sequence of Dead Space 3, players will encounter Necromorph variants of the aliens. These Necromorphs, according to Dr. Serrano, were thawed out of ice by the biology team as they attempted to communicate with them, unaware that they were infected monsters and not the alien lifeforms themselves. It is most likely that these alien Necromorphs rekindled the infection in June 2314.
- Their technology (most notably the Machine) would only function with the Aliens' DNA. Serrano commented on this when realizing the Machine wouldn't work with a Codex programmed by an Alien-turned-Necromorph, hence why Rosetta, frozen solid and preserved from the Necromorphs, was so vital to the project.
- It is noteworthy that the masks worn by Unitologist Slashers (seen during Isaac's trek through the Church of Unitology on Titan Station) bear striking resemblance to the Aliens' heads.