Featured in the 2001 comedy film Evolution (and its animated television series based on movie); these lifeforms are based on nitrogen, rather than carbon; and have a much faster metabolism than Earth creatures; as they are able to evolve into new species in a matter of hours or days, rather than millennia. They also have ten different fundamental bases in their DNA; whilst Earth organisms have only four. Exposure to great temperatures like explosions or fire causes these aliens to increase size tremendously.
Their origin is unknown. They arrive on Earth as blue-colored unicellular lifeforms inside a meteorite and soon some of them evolve to become multicellular, eventually spawning an entire ecosystem within the meteor's crater, which includes species analogous to lichens, worms and insects.
All Evolution lifeforms reproduce asexually, which is interesting given that this form of reproduction is often believed to be associated with slow, not fast, evolution. After a few days, some vertebrate analogues escape and start giving rise to several reptilianoid, and later mammalianoid forms, which threaten to take over Earth's entire ecosystem in no more than a few months. The only thing slowing down their progress is that they cannot breathe oxygen properly, making them slow and short-lived. Eventually however, some of the aliens do evolve the ability to breath oxygen and become far more dangerous. Based on the projections by Dr. Reed's team, it is estimated that the alien ecosystem will overwhelm the United States in two months.
In an attempt to wipe out the aliens, the USA military decides carpet-bomb the meteor site with napalm, supposedly destroying the center of alien activity. They were unaware of the creature's biological response to such explosions, however, and instead of killing the aliens the explosion results in the smaller lifeforms growing uncontrollably and fusing together to form a gigantic, amoeboid meta-organism. In the end, a weakness of the aliens is discovered: selenium, which is in the same position relative to nitrogen as arsenic is to carbon. Using grand quantities of selenium the giant alien is poisoned and killed.
In the animated television series, the aliens are referred to as "The Genus". The tv version does too have an intelligent form, called SCOPES.
|Unicellular amoeboids organism with a distinguished blue coloration, possibly caused by their nitrogen-based nature. These are the creatures originally found within the meteor, bleeding from the rock like a bluish goo. Where they came from and how they ended up on the meteor are subjects worth of speculation.|
|Multicellular lifeforms evolved from the original single-celled beings within a few hours.|
|Small, yellow fungoid-like organisms soon started to colonize the cave where the meteor fell. They secrete a dense mist which allows them to survive in Earth’s atmosphere.|
|Tiny flatworm-like creatures live in great numbers among the fungoids within the mist. They reproduce by binary fission.|
|A rat-sized aquatic amphibianoid creature evolved presumably from the flatworms and managed to escape the cave system, invading the nearby lake.|
|Inside the cave, after a few days, a rainforest-like environment has emerged. Protected by the atmosphere they have produced, thrive several species of fauna, flora, and things in between.|
|A crustaceanoid scavenger crawling on the rainforest floor.|
|Another type of crustaceanoid scavenger found on the rainforest floor.|
|A medium-sized creature which feeds on the aforementioned crustaceanoids in the rainforest.|
|An oddly symmetrical lifeform, about the size of a dog, with six pairs of long, jointed legs which move in synchrony. It has heads on both ends of its body, flicking out its tongues in search of food.|
|A small insectoid parasite. Its snout is sharp enough to cut through clothes and skin, and the whole creature enters and crawls under the skin of its victim before heading to the digestive system. It is not clear if it intends to parasite or lay eggs, or both.|
|Meanwhile in a nearby lake the amphibianoid has evolved into an aggressive dog-sized aquatic reptilianoid which ambushes prey like a crocodile. After coming out of the water, it soon dies, choking to death due to the oxygen level of the atmosphere.|
|Another type of amphibianoid attempting to colonize land and ultimately failing and dying of suffocation. Despite its timid and harmless appearance, it hides a Xenomorph-style inner mouth armed with sharp teeth and small pair of eyes.|
|A winged reptilianoid, very dragon-like in appearance. Many of these were found dead on the desert before the discovery of a newborn with a mutation that allowed it to breathe oxygen. After invading a shopping mall the beast was shot dead.|
|A blue humanoid creature finally evolves in the rainforest. It shows signs of both great intelligence and extreme aggressiveness, managing to operate the elevator and attacking people in the military base. It is very likely that this was the species that would take over should the aliens manage to colonize Earth.|
|A rapidly-growing fleshy mass with expanding tendrils formed by the growth of alien microbes upon exposure to extremes of heat. The amount of exposure to heat greatly influences the size of the mass. A simple petri dish of the microbes lit by a match caused exponential growth that spread over the table, wall and window, while the evolving mass in the cave rapidly mutated into larger sentient tendrils. It should be noted that continuous exposure causes the organisms to develop further into a giant amoeba.|
|A huge amoeboid creature created by the napalm explosives at the meteor site. The extreme heat caused the already fast-evolving alien ecosystem to grow almost instantly into a monstrous creature, consuming all other aliens in the process. It should be noted that this final form has resemblance to the aliens' original unicellular forms.|