Brethren Moon

Brethren Moons are moon-sized organic creatures that exist in the Dead Space universe. Believed to be the apex stage in the life cycle of the Necromorphs, these beings are the source of the telepathic signals given off by the alien relics known as Markers.

Source and Convergence
The Brethren Moons, though their origins are unknown, are a series of moon-sized creatures throughout the galaxy that consume all organic life that they encounter through the use of their Markers.

The Moons consume new worlds by sending out Black Markers, which travel through space and impact planets; in the case of Earth, the Black Marker was carried inside an asteroid that struck the Yucatan Peninsula around 65 million years B.C.E. It is unknown if the Moons specifically target worlds that show promise for intelligent life, or, as theorized by the Unitologist leader Jacob Danik, if the Markers are actually responsible for encouraging the evolution of intelligent species.

The Markers broadcast an electromagnetic signal, originating from the Moons themselves, that mentally affects intelligent beings. This signal manifests either as dementia or as a compulsion to replicate Markers through artificial means. Because of this, along with the fact that the Markers' signal represents a source of apparently limitless electromagnetic energy, intelligent species are driven to create Marker copies—Red Markers—that are then inevitably distributed throughout their territory. However, the signal has another function: it can alter necrotic tissue on the molecular level, causing corpses to reanimate and become Necromorphs.

After a Necromorph infestation has claimed the majority of a planet's population, many Markers on the planet will initiate a Convergence Event—the birth of a Brethren Moon. Once the Convergence begins, the necrotic flesh of both Necromorphs and dead tissue within the Markers' reach are flung into the stratosphere, where they begin to form together into a new Moon. The Moon not only absorbs organic material, but appears to absorb fragments of the planet as well.

The creature is only finalized once the creators of the Markers are absorbed along with the planet's entire biosphere. Once the makers have been absorbed as well as a large portion of the biosphere, the Marker itself gravitates to the central heart of the moon, so that it can broadcast telepathically to the rest of the formation as well as release broadcasts to other nearby Markers. It is currently unknown what happens to the Moon once it has absorbed all life on its birth site, but it is assumed that the mass travels to the next nearest source of organic life to continue feeding.

Earl Serrano speculates that all life between the origin of the Moons and humanity's home system may have been extinguished and that the Moons are largely responsible for the destruction of countless species; in their quest to absorb all organic tissue within the universe, much of our galaxy is left in a state of "dead space". Serrano also discovered that the Moons form a network spanning the entire galaxy; this network enables them to communicate with each other. The Markers influence the affected races to build more Markers, which in turn trap and assimilate other species, expanding the Moon network.

Dead Space 3
During the events of Dead Space 3, Isaac Clarke comes to realize that the signals that Markers receive are a distress call from the incomplete moon of Tau Volantis, which was forced into a hibernation state when the alien race it was attempting to lure and assimilate built a machine to freeze over the entire planet, preventing the monstrosity from becoming whole and continuing on in the galaxy. As a result, the Moon began deploying distress signals through its alien Markers (like Make us Whole or Turn it Off), hoping to bring new organic beings to disable the machine preventing its growth, which would allow it to continue its assimilation of the galaxy.

The faux Markers that Isaac had been facing were attempting to continue the "Brethren Chain" of Moons by circumventing the hibernating Tau Volantis Moon. He also realizes that if the moon is freed from its frozen hibernation, any location within the galaxy with a still active Marker will begin the ultimate Convergence, continuing the growth of the Tau Volantis Moon.

The Moon's completion would then awaken the other completed Brethren Moons which would subsequently head for the Marker locations and devour all organic life present, resulting in the inevitable destruction of humanity and possibly all life in the galaxy. In the final chapter, Isaac manages to reconfigure the alien machine and destroy the Tau Volantis Moon. The Moon's destruction causes all the Markers to cease broadcasting their signals, ending the danger they pose to the rest of the galaxy temporarily.

However, during the Tau Volantis Moon's reawakening, it somehow managed to contact the other Brethern Moons, even though the Moon wasn't fully completed. When Isaac and Carver defeated the Tau Volantis Moon, the Brother Moons awakened and began converging on the last source of life in the galaxy; Earth.

Dead Space 3: Awakened
After the destruction of the Tau Volantis Moon, Isaac Clarke and John Carver somehow survived their fall from orbit. The two made it to the surface and noticed the fallen Moon out on the horizon of Tau Volantis. Isaac believed that after the Moon's destruction, the Marker signal would cease and therefore there wouldn't be any more Necromorphs. When Isaac and Carver reached the nearest Suit Kiosk and Bench, they suffered a brief vision of Brethren Moons, realizing the Necromorphs are still active.

The remaining Unitologist soldiers on Tau Volantis start to lose faith in Unitology when the Moon is destroyed, believing that there would be no Convergence or Rebirth, only death. However, a Unitoligist fanatic heard a 'voice' from the awakened Brother Moons, saying "We are coming, we are hungry."

His faith in Unitology reaffirmed, the Circle member began to gather all the remaining Unitologists into orbit into his new, fanatical cult of mutilation and sacrifice. Only a few Unitoligists resisted; either mentally broken by the Moon's signal and repeatedly chanting "They are hungry, they are coming" as a mantra, or outright attempting to resist and escape their insane, former brethren.

Isaac and Carver reached the Terra Nova, all the while subjected to painful visions of the Brethren Moons. Isaac began to suspect that the Moons were manipulating them; by taking the ship back to Earth, they may well end up leading the Moons back with them. Isaac decided to destroy the Shockpoint Drive and trap them at Tau Volantis forever, leaving the Moons without direction. Carver, seeing that Isaac is growing more paranoid, threatens him, determined to recover the drive and return to Earth.

The pair fight the Cult Leader, and after defeating him learn that the Moon's visions were themselves another ploy. They already knew where Earth was, and only turned Isaac and Carver against each other to prevent them from warning Earth in time. Knowing they have to hurry, Isaac and Carver install the salvaged ShockPoint Drive on the Terra Nova and overload the ancient reactor of the ship to power it up, shocking just before the ship gives out entirely.

Arriving at Earth, Isaac and Carver tried to contact the authorities through several channels to relay their warning, each time being met with static. After several tries, a transmission breaks through: the gurgles and snarls of many Necromorphs. The two are shocked when they see Brethren Moons rising from the other side of Earth, already scouring the surface of the planet with their tentacles. The scene ends after a Brethren Moon begins to rise in front of the Terra Nova, crashing the ship and knocking Isaac and Carver unconscious.

Appearance and Behaviour
Essentially, the Brethren Moons are monumentally huge entities that resemble moons, but there is more to them than that. The moon-like surface almost acts like a shell casing to shield a truer form,. They have colossal, almost worm-like tendrils and tentacles spouting out from a big fleshy mass. Some of the tentacles could be hundreds of miles long. Within the tentacles lies a very distinctive head that holds 3-5 big, yellow eyes and a digestive system, possibly holding its own brand of organs necessary to consume whole civilizations as well as a gigantic gaping mouth which is protected by the tentacles, very similar to the beak of a squid or octopus.

Research notes from Dr. Serrano speculate that the Moons are drawn to species that have grown and spread throughout the galaxy, and have become overpopulated and starved of resources. He speculates that this is how they discovered the Alien race of Tau Volantis, who once were an empire trillions strong however the aliens were resourceful and froze the entire planet with the Machine at the cost of their own lives.

This theory is backed up by the limitless energy the Markers radiate, encouraging species with a desperate need for resources and energy to focus on building more Markers across their systems. This would make the species less able to enact quarantines effectively.

The moons are sentient organisms, able to communicate via a form of telepathic signal, as with Isaac and Carver. During the hallucinations where they speak to Isaac and Carver through their "Prophet", the Cult Leader they display a kind of hive mind-mentality, referring to themselves in the plural. The moons appear to regard themselves as invincible, omnipotent and divine, at one point referring to themselves collectively as a "god". The Brethen Moons also seem to speak rather with a polite and calm form, a strong contrast to their general nature.