Genus (Evolution)

Genus are name given to extraterrestrial lifeforms that serves as primary villain in 2001 comedy film Evolution as well as its TV Series sequel Alienators: Evolution Continues.

Origin
Genus lifeform’s 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.

Though not confirmed, the aliens are survivors of the destruction of their home planet.

Characteristics
Genuses 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. How fast they evolved revealed to be depended on the heat: The higher the temperature, the faster they evolved. It means exposure to great temperatures like explosions or fire causes these aliens to increase size tremendously. This capabilit also presumably enable Genuses to survive the destruction of their planet.

They also have ten different fundamental bases in their DNA; whilst Earth organisms have only four.

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.

Evolution (2001) Film
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.

Alienators: Evolution Continues
Whilst in the film majorities of Genus Lifeform villains mostly instinctive creatures that obvioulsy pose the threat to Earth, they serves as bigger threat in the TV Series. A large number of Genus worms that yet to evolved revealed to have escaped from the crash site and spread across America, which led the protagonists of the film formed organization called Alienators to combat them once more. The situation ultimately become complicated with the emergence of SCOPES, highly evolved, power-hungry race of Genus lifeform whom goal is to kill, eradicate, and slaughter all life in favor of their kind that they view as better, superior organism. SCOPES considered Earth lifeform, particulary humanity, a useless and unnecessry parasite to the planet.