The atmosphere's main components are similar to Earth's; 71% nitrogen, and 23% oxygen. However, there is a high level of carbon monoxide, which constitutes 3% of the atmosphere. This is more than enough to be fatal to humans in a very short exposure. It also contains small amounts of argon, as detected by the spaceship Prometheus.
It is uncertain if there were any existing life forms, before the Engineers, but at some point, a group of Engineers put up an outpost on the planet. It is speculated by Janek that it was some sort of military base set up by the Engineers to build biological weapons before they lost control of them. There are worm or centipede-like creatures within the domes but it is unknown if they are native or foreign. The worm like creatures are altered forms of what appear to be Earth Mealworms. These beings eventually go through a mutation process similar to Fifield's and become the lethal Hammerpede.
Thousands of years earlier, the Engineers came to LV-223 and used the moon as an outpost for producing and/or experimenting with the Black Liquid pathogen. They also built large, dome-like structures on the surface which their ships were hidden under. However, at some point approximately two milennia before the late 21st century, the Black Liquid pathogen apparently escaped and went out of control, and the entire Engineer outpost on LV-223 was wiped out, except for one Engineer who remained in stasis aboard his ship.
In 2093, approximately two-thousand years later, the USCSS Prometheus and its crew arrived on LV-223 and investigated into one of the buried Engineer ships. However, while they were in the ship, they accidentally released samples of the black liquid that were stored aboard, and subsequently awakened the sole surviving Engineer.
The Engineer attacked and tried to kill the remaining crew of the Prometheus who had not been killed due to the release of the Black Liquid. However, it was defeated by crew member Elizabeth Shaw when she set a Trilobite on the Engineer. Shaw and the only other surviving crew member, David, left LV-223 shortly after in another one of the buried Engineer ships, Shaw leaving a warning message. In the crashed lifeboat, the impregnated Engineer died, birthing a Deacon.