Leviathan

Leviathans are a crucial plot element of Metroid Prime 3: Corruption. Their sole purpose is to spread Phazon from the celestial body known as Phaaze once every century, (this is mentioned in the Metroid Prime Trilogy artbook: Every 100 years, seeds, similar in form to meteors, would be fired from Phaaze[...]) and to corrupt planets across the universe in order to create more Phazon-based planets, similar to Phaaze. The core of the Leviathan is very strong and can only be destroyed by a stream of Phazon or a powerful laser blast. These creatures were notable not only for their ability to create Phazon, but mostly because of their most powerful ability: generating wormholes which allow them to travel anywhere throughout space.

There have been five recorded cases of Leviathan impact.


 * Tallon IV's Leviathan
 * Aether's Leviathan
 * Bryyo's Leviathan
 * Elysia's Leviathan
 * Pirate Homeworld's Leviathan

Infancy
Leviathans are the "children" of Phaaze. Born in a serpentine womb deep within the planet, they feed on vast amounts of Phazon energy until they develop a Phazon core, which marks their transition into adolescence.

Before this, they are extremely unstable, though naturally extremely resistant, and cause massive explosions if damaged before full maturity. Once they reach adolescence, the Leviathans are slowly pushed upward to the surface until they mature to their adult size. The oldest Leviathans are up closest to the surface while the youngest are below. As Leviathans are launched into space, the younger ones move closer and closer to the surface. As mentioned above, an unspecified number of these creatures are launched every 100 years; the reason behind this century-long wait is unknown though it might be the required time for infants to reach full maturity. Finally, once Phaaze has found a planet to corrupt, it launches the Leviathan into space, in hopes of impacting a planet. It is unconfirmed, but this is likely the creature on Metroid Prime 3: Corruption's title screen.

Biology
Leviathans are a silicon/Phazon-based bioform in that, at full maturity, appear to be made of a rocky substance (perhaps a form of Phazite) which is likely why information pertaining to them refers to them as meteors. They are covered with large patches of Phazon and have long tentacles growing out of their sides. The inside of a Leviathan appears similar to a cave containing various Phazon based life and Phazon generating organs. The passages that lead to the core chamber of the Leviathan appear as transparent tubes, similiar to veins, but without liquid within them. There are doors in the Leviathan that seem to be a type of sphincter valve with a weak energy field covering it. The core chamber is a large spherical room, with many pulsating and moving objects which may be organs. The Phazon Core itself resides at the top of the chamber in a sealed sac-like room. The Core appears similar to be a large, round, insectoid creature connected to the ceiling by several cords that it moves around with. It is covered in Phazon growths and has several eyes and a mandible-like mouth. The chamber is also usually where the Leviathan's guardian resides. Because the Leviathans on Tallon IV and Aether were not expressly shown, it is difficult to say which attributes of the three featured in Corruption are characteristic of immature Leviathans and which ones apply to all.

Actions
After ejecting from Phaaze, the Leviathan will create a wormhole to shorten its journey to the intended planet. The Leviathan will home onto its closest target and impact the planet, spreading Phazon from the collision. The Leviathan then creates a Phazon Core which slowly seeps its way into the planet, spreading corruption and replacing the ecosystem with one that is Phazon-based. The Leviathan attracts a native creature and corrupts it with massive amounts of Phazon. The corrupted creature serves as the Leviathan's guardian, to protect its Phazon core. Some time after this, the Leviathan itself will die, leaving behind the "husk" of its body.

Controlled by Dark Samus
Once Dark Samus returned to Phaaze, with the help of the stolen Aurora Unit 313, she was able to control when and where a Leviathan would launch and land by fusing them with the stolen technology. This allowed her to spread Phazon throughout the universe far more effectively and strategically. She used this ability to launch four Leviathans: one to the Pirate Homeworld (to corrupt the resident Pirate forces and thus secure a powerful army), one to Bryyo (to seize control of the planet's priceless Fuel Gel and cut off the Federation's supply of it), another to Elysia (a Federation spy base, originally built by the Chozo), and the fourth to Norion (one of the Federation's greatest naval strongholds).

The Leviathan that was aimed for Norion was destroyed before impact, the other three survived and were able to pour great amounts of Phazon into each planet. The ones in Bryyo and Elysia were protected by great energy shields, while the Space Pirate Homeworld one was so heavily defended that only one cargo route was allowed to reach the Leviathan itself. In orbit around the Pirate Homeworld, the Space Pirates had outfitted a fifth Leviathan with weapons; however, with Samus's help, the Federation took control of it, using its wormhole-generating abilities to warp to Phaaze.

Impacted Planets
Fifty years prior to the first Metroid Prime, a Leviathan impacted Tallon IV and brought Phazon to the planet. There was a creature living within this Leviathan since its launch from Phaaze, named Metroid Prime by the Space Pirates, that was the Leviathan's Guardian and was feeding on the seed's Phazon. Several days after its impact, the Chozo residents of Tallon IV were able to greatly slow down, if not completely stop the spread of Phazon on the planet by building a temple named the Cradle, which used an unseen containment field. This particular Leviathan seems to have many characteristics that differ from its brethren, such as having a higher lethality rate towards local populations than seen on the Pirate Homeworld. This suggests that the molecular composition of the Phazon brought to Tallon IV, and possibly also that which was brought to Aether, were from fully matured Leviathans compared to the ones seen in Metroid Prime 3: Corruption, as Dark Samus (a.k.a, Metroid Prime) would have no doubt been impatient to wait 100 years for them to grow and thus launched them prematurely during her reign. Fans speculate the Impact Crater is the Leviathan for Tallon IV, but since there is no visible sign of the Leviathan itself in the game, it can be speculated that the creature was consumed by its Guardian, Metroid Prime, due to the creature's hunger for Phazon, just as it is assumed that Prime also absorbed the seed's Phazon Core, giving it the ability to produce Phazon. This might explain why the hypertoxic substance found in the Impact Crater was not encountered on Phaaze: It may have been produced by the decay of the Leviathan's body or the surrounding environment, namely the additonal pressure present in the Crater due to the Cradle's containment field, which may have concentrated the Blue Phazon into Orange Phazon. Alternatively, since Samus teleports directly into the Impact Crater, it is perfectly logical to suggest that the Leviathan does in fact continue to exist in its entirety; no outside view of it is seen merely because the Artifact Temple is built over it and the crater in order to contain it.

Twenty years before that, a Leviathan impacted planet Aether, visited in Metroid Prime 2: Echoes. However, due to the instability of Aether's planetary energy, another dimension, known as Dark Aether, was ripped open; the Leviathan itself, along with nearly all of its Phazon, was teleported to Dark Aether at the moment of impact. It is speculated that the Emperor Ing serves as the guardian of the Aether Leviathan Core.

Several months after the events of Metroid Prime 2: Echoes, a Leviathan impacted the Space Pirate Homeworld. This was the first one to be controlled by Dark Samus. Ridley would later be chosen as its guardian.

A few months after that, Dark Samus sent three more Leviathans to corrupt a number of planets. They were headed to Norion, Bryyo, and Elysia. The one aimed for Norion was destroyed before impact, but the ones headed to Bryyo and Elysia were unharmed until Samus Aran destroyed the Phazon Cores within them. The Bryyo Leviathan's guardian was a corrupted Mogenar War Golem, while the Elysia Leviathan's was a massive robot called Helios. Interesting to note is the fact that the first Leviathan seen in Metroid Prime 3: Corruption was easily destroyed by Federation tech, while Luminoth and possibly Chozo technology, were unable to destroy their respective Leviathans at all. This is considered strange as both mentioned species are highly evolved sentient creatures whose technologies far surpass the Federation's. This leads to the mentioned theory that the Leviathans launched prior to Dark Samus' control over Phaaze were at the peak of their growth, possibly having a stronger surface. Though in case of the Chozo on Tallon IV, it may have simply been due to the fact that the Chozo of that planet chose to build a colony from natural materials and so lacked the technology needed to destroy the Leviathan. It is also mentioned that the Chozo were, before impact, ascending to another dimension, leaving their physical bodies waiting for their consciousness to return; they were violently pulled back to the physical realm at the time of impact. In the case of the Luminoth, no piece of information is given other than a lore that described them using various weapons against the coming Leviathan before impact, with no avail. They could do nothing but wait for the inevitable. Careful inspection of a Leviathan reveals it to contain more bulk on its front than the rest of its body; this leads to another explanation that the Federation were able to destroy Norion's respective Leviathan by attacking its side which is seemingly less armored than their front (it is logically plausible that the front is heavily resilient to resist collision with a planet and deliver its Phazon cargo intact).

It is unknown if any other planets were corrupted by Leviathans before the events of the Metroid Prime series, though it is likely. If so, it is unknown if these planets "survived" the destruction of Phaaze. When Phaaze was destroyed, the Pirate ships that were powered by Phazon fell to pieces and Samus became completely free of corruption, but other completely corrupted planets may have been powerful enough to survive on their own without the help of Phaaze.

Etymology

 * Leviathan (Hebrew: לִוְיָתָן, Standard Livyatan Tiberian Liwyāṯān; "Twisted; coiled"), pronounced /lɨˈvaɪəˌθɑn/, is a Biblical sea creature first known to be referred to in the Old Testament (Psalm 74:13-14; Job 41; Isaiah 27:1). The word "leviathan" has become synonymous with any large sea monster or creature. In the novel Moby-Dick it refers to great whales, and in Modern Hebrew, it means simply "whale".