This world was discovered by Voyager sensors in 2372. Initial sensor scans that the starship took of the planet gave readings of high amino acid and protein counts. Normally, this would indicate healthy plant life; however, there was no evidence of plant life on the surface of this world.
Trigemic vapors covered the planet like a curtain, and anomalous EM disturbances occurred all through the atmosphere. These disturbances generally prevented transporting to the surface of the planet, but windows allowing transports occurred around every thirty hours. Some readings suggested a planet early in its evolution, almost like a primeval Earth.
However, these readings did not rule out flora or even fauna with absolute certainty, and indeed the occasional plant was observed later. Humanoid life could operate on the surface, though skin exposure to the vapors was an issue. Despite the general hostility and the planet being a full day out of Voyager's way, it was still targeted for a mission by the crew, in the hopes of replenishing diminishing food reserves aboard the ship. This decision was also influenced by the lack of other known promising M-class planets nearby.
It was soon determined that this planet was used by a space-faring Reptohumanoid species as a birthing-ground. After their offspring hatched, they used the vapors to feed themselves until they were retrieved by their parents. Reptohumanoids might attempt defending the planet. (VOY: "Parturition")