Gauna are an alien species that feature in Knights of Sidonia.
The Gauna (奇居子) were large space dwelling entities that prowled the universe. Their existence was discovered at sometime prior to 2171 AD when a Mass Union Ship was detected at the outer edges of the Solar System. In 2371, the ship arrived at Earth where it dropped 46 Gauna on the surface of the planet. Once there, the Gauna began to absorb human life on the surface including marine life that were consumed by them. As a result of the Gauna, they managed to split the Earth into two hemispheres as they burrowed down into the planetary care with kilometer long placental arms emerged from deep inside the world. A thousand years ago, the solar system was destroyed by the Gauna with humanity forced to flee on seedships such as the Sidonia who escaped to the stars where they survived despite the odds. Around 600 years ago, the Sidonia encountered a large deep space artifact of unknown origin whose metal was composed of a unique substance that could kill the True Body of a Gauna. This Kabi metal was harvested and used to create spear weapons known as the Kabizashi that were a precious weapon needed to fight the Gauna. Around this time, the scientist Ochiai was conducting secret experiments in creating artificial hybrid Gauna but later went rogue where he jettisoned the Kabizashi. Two Gauna slipped past the defenses of the Sidonia and nearly wiped it out with the crew only saved when the pilot of the Tsugomori arrived with the Kabizashi to eliminate them. As a result of this Fourth Gauna Siege a century ago, this was due to food processing capabilities being lost and humanity surmounted through genetic engineering to allow humans to adopt photosynthesis.
For over a century, the crew of the Sidonia claimed that they had not had any encounters with the Gauna. This ended during a sortie formed by a mining squad for ice that arrived at dwarf planet where they accidently awoke a Gauna. During the engagement, a pilot Eiko Yamano was consumed by the creature and the mining squad was forced to flee as the Sidonia fired the heavy mass cannon to obliterate the asteroid where the Gauna resided though this was seen only as a temporary measure. A Mass Union Ship was situated around three light years from the Sidonia as it sought to escape the creatures. The damaged Gauna from the asteroid shed its placenta and moved slowly towards the direction of the Sidonia where it where it was expected to catch up with the ship in three days. Four of Sidonia's top Garde pilots were dispatched to intercept and kill the Gauna with three of them being killed whilst the four was badly wounded. It as only the efforts of Nagate Tanikaze whose Garde had a Kabizashi and he used it to kill the Gauna with him being hailed a hero for his actions. However, the Sidonia later detected a group of four merged Gauna that had been hiding and approaching the ship leading to a deployment of Gardes sent to kill it. The creature was eventually killed but this came at the loss of Shizuka Hoshijiro who was killed in action against the Gauna. Afterwards, a large Gauna cluster had engulfed an asteroid that was on a collision course with Sidonia who dispatched a large force to eliminate the creature. Following heavy casualties, they successfully managed to destroy the host core thus terminating the creature.
They were composed of two components; the first being the Placenta (胞衣 ena?) and the second being the True Body. The True Body core of the Gauna resided in the location analogous to a human brain and spinal cord. A typical strategy was to break open the exterior to allow access to this region whereby a special weapon was needed to strike at the core. Once the core was destroyed, the Gauna ceased activity and the exterior placenta disintegrated. The only weapon capable of such a task were special Kabizashi spears carried by mecha. If Placenta was separated from the True Body prior to the destruction of the core then the Ena was capable of surviving on its own though it was initially no known for how long it could remain independent. Other forms of attacks did not harm the creatures as they simply regenerated their wounds. In one example, a Gauna's body was damaged from a starship's heavy mass cannon but it simply reincorporated its separated parts and started following the space ship. A pod of Gauna were able to survive the destruction of a rogue planet that they resided on without any harm to themselves.
The Placenta was extremely malleable allowing it to be used to take a variety of forms from tentacles to grab prey or even become the equivalent of technology. This can lead to the biological equivalent of Heigus Drives that allowed for space travel or even Heigus Beams. The Placenta was capable of being turned invisible allowing the Gauna to appear invisible to scanners. More precise manipulation of the Placenta could see it mold to form mecha such as Gardes. Following contact with any matter, a Gauna was able to assume the form of that substance such as consuming a human and turning into a giant version of said individual. Amore refined version of the Gauna included making perfect copies of humans that included the individuals memories. A group of Gauna were able to able to merge together into a larger mass. These large pods could contain multiple core True Bodies but only a single one served as a host that kept the merged form together.
Gauna were known to be powered by Heigus particles that served as an energy source. Presence of ultrahigh Heigus particle reactions was indicative of a Gauna presence. Communication was believed impossible with the Gauna and that humanity needed to show unwavering strength against them.
Mass Union Ship were vessels formed from the Gauna that had incredibly long range. Some of these Gauna pods were so massive that they could be around 8,000 times the size of a seedship like Sidonia. Typically, Interplanetary Missiles (IPM) were not used against such Gauna despite their massive size as they were quickly able to adjust their course to avoid attacks and match the movements of space craft. One kind of Gauna was given the designation of an H-Type. After the assimilation of Hoshijiro, a new type of Gauna began to form in the shape of Gardes that included pilots. The Gardes were given the designation of Crimson Hawk Moths with them able to go faster than regular Gardes and even go beyond their range. These mecha-type Gauna were able to use the Placenta to form weapons that they used to battle enemies. Inside the Crimson Hawk Moths were Gauna that formed a complete replication of a human pilot.
- The Gauna served as the primary antagonists in Knights of Sidonia.
- Knights of Sidonia: