Gaia

6,000 years before Keter was colonized, the first colony of Gaia landed on what they thought was going to be a garden world. After their 500-year multi-generational journey the colonists were not happy to discover upon landing their city that the atmosphere was toxic to humans.

At some point roughly 40 million years ago, a form of algae began to produce chlorine dioxide instead of pure oxygen as a form of respiration. For the algae this worked well as it eliminated competition, but soon the entire ocean was devoid of most life. Eventually other plants evolved in the oceans that also emitted the toxic gas, slowly complexity began to arise again in the ocean.

On the surface, life had more time to adapt. Many animals died, and those that remained were very small crustacean like critters with shells that evolved over time to protect them from the acid rains that were forming. Mollusk like creatures also evolved, though their shells are softer and more like plastic than the shells we are aware of.

Plant life changed too. It got thicker and darker, flowering stopped, but plants produced seeds that broke off during the acid rainstorms with hard outer shells that would slowly dissolve after the seed had been deposited far away. Human colonists would also remark on the terrible smell of native plant life, claiming that after a rain the air smelled like melting plastic.

The colonists themselves were forced underground, and for hundreds of years they were hampered by slow expansion, mostly going deeper underground, and building sprawling glass covered gardens on the surface.

The Gaians managed very slowly, over 5,000 years to rediscover the technology that brought them to this hellish world. Earth as we know it had been forgotten, now the name of their deity. The Gaians now re-emerge from their planet in search of their distant god.