Trekipedia

Planet, Class-G

Geocrystalline. Age ranged from 3-4 billion years. Diameter was 10,000 to 15,000 km. Typically located in the Ecosphere of a planetary system. Surface was still crystallizing, atmosphere contained carbon dioxide, some toxic gases. Eventually cools to become Class K, L, M, or N. May contain some primitive single-celled organisms.^[1]