The prawns, aliens, outlanders, or non-humans of District 9 are a spacefaring race of sentient beings, with highly advanced technology and spaceship engineering. Their reasons for coming and/or colonizing on Earth are unknown so far. The non-humans are bipedal, several feet taller than humans, and have dark thick shell-like skin as well as a mass of facial tendrils. It is hypothesized that these tendrils are somehow involved in the mastication process, but it has not been proven. These aliens are also very strong. A non-human has been observed taking hold of an MNU soldier's arm, and placing his foot on his chest. He kicks outward, resulting in the soldier's arm being ripped off, as well as sending him flying several yards back. In another case a non-human was observed breaking a shotgun in half with a single one-handed blow.
According to David Meng of Weta Workshop, the vast majority of the aliens are worker-class "drones", explaining why they were so lost and ineffectual. Christopher Johnson is one notable exception to this rule. None of this non-human social structure made it into the film; perhaps director Neill Blomkamp is saving it for a future film? Uncomfirmed by director Neill Blomkamp: In his previous film "Alive in Joburg " which inspired District 9, the aliens referred to themselves as Poleepkwa. Interested parties have contacted the director on whether or not this term can be officially applied. There's a possibility that because of the uniquely hominid shape of their bodies and comprehension of English that their society is derived from humans that have been captured and metamorphosed into prawns by the same liquid which is the basis of the main character's transformation. The prawns then would actually be a representation of humans taken out of society and allowed to experimentally create a society and language out of scratch from perhaps 1950's era abduction stories and UFO interest having been people that have actually disappeared to become the experimental culture-less prawn population, which they clearly do not do (Which could also be seen as a reference to the American goverment's actions on indigenous Americans in that they were placed into concentration camps and forced to speak in English and live as they were told, which would be the same as simply losing an entire society's thousand or more years of social and cultural evolution). This and the fact that the transformation that the liquid creates onto the main character is a very complex biological one which would be literally impossible as science currently understands life and so might hint that the liquid is created for the sole purpose of it, with a double purpose of being a fuel.
The non-humans have a variety of extremely-powerful energy weapons. The weapons can only be activated by alien DNA, which means that no human can use them (with the sole exception of Wikus). The weapons shown in the film are mostly energy-based, but several clips prove otherwise, for example, at one point, Christopher can be seen using one that appears to handle like an assault rifle when he and Wikus stormed MNU headquarters. Wikus uses a gun in the Nigerian gang base capable of producing a shockwave blast powerful enough to blast a human through a wall at high speeds. Even a near miss can send someone flying through the air as shown in the film. Another weapon of note is a large alien mech that Wikus piloted near the end of the film. The suit appears to have a number of other alien weapon capabilities integrated into it, along with a magnetic field generator that allows it to catch enemy projectiles and launch them right back at the enemy.
The most well known weapon is the ARC gun. It fires a huge charge of electricity and rapid molecular expansion of gas and fluid. In a soft biological target, an ARC gun strike can result in a catastrophic explosion of blood and gore. But even a near miss can cause superficial burns and keep an enemy subdued.
The Homeworld of the Prawns is mentioned to have 7 moons, it is also noted by Christopher to his son that it is several times bigger than Earth. Due to the fact that the Prawns can breathe Earths oxygen atmosphere, it is very likely that their Homeworld has very similar conditions as on Earth. This would also explain why the Prawns landed on Earth instead of any other nearby planets on their route.
However no hints are made in the movie where this Homeworld is exactly located or whether it is the only world inhabited by his species. At the end of the movie, Christopher can be seen guiding a navigational system in his craft, which shows a map of several galaxy-like structures, implying the Prawn Homeworld may be not located in the Milky Way. It is also shown that the Homeworld is located in a globular cluster.