Surface: Continued crystallization
Atmosphere: Carbon dioxide, toxic gases
Age: 3-4 billion years
Equator diameter: 10,000 to 15,000 km
Life: primitive unicellular organisms
Evolution of the planet: H, K, L, M, NO, P
Once the core of a class F planet is sufficiently cooled and volcanic activity decreases, the planet is considered a class G. Oxygen and nitrogen are present in a certain amount in the atmosphere, leading to increasingly complex organisms such as primitive vegetation, algae, and animals like mushrooms and jellyfish. Once the surface has cooled, class G can further develop into classes H, K, L, M, N, O, P.