A tropical appearance with terrain features such as dense forests, verdant grasslands, and thick swamps. The most "Earthlike" of the three.
In Rising Tide, Aliens upon these worlds appear cosmetically, and behaviorally exactly the same as the alien variants in the basic game, although there are far more of them then usual and they are statistically weaker due to how accommodating conditions are for life.
The feeling that every inch of this planet is alive is not an illusion. The wildlife of this planet is abundant, both on the micro and macro scale. This appears to be because of how conducive the atmosphere on the planet is to supporting plant life. The abundance of food sources allows creatures to survive with relative ease. This means that the inter-special competition is relatively low, and results in a large quantity of fauna. It also, however, has resulted in weak natural selection, which can be counted as both a blessing and a curse.