Civilization's End

We can now piece together what became of the Ilanii's attempt at immortality. It appears that, far from bringing them everlasting life, they created a terrible menace - a swarm of microorganisms capable of multiplying rapidly and almost instantly devouring any organic matter... as must have happened to our team's lost member. The resulting cataclysm wiped out much of the population. The survivors splintered into two groups: one, unwilling to give up …, took to the depths, recreating their civilization in air-tight pockets such as the one we found. However, this solution proved unsustainable in the long run, and eventually the microorganism found its way into their habitats; the caves became their tombs. The other group instead went into exile, enforcing a planetary quarantine by utterly obliterating the surface, rendering it uninhabitable. They would henceforth live in small enclaves and dedicate themselves to preserving the lost knowledge of their civilization, eventually morphing into one of the ancestors of the modern ….

The command below will trigger the "Civilization's End" event in Stellaris:

When this event fires, you can choose between these 3 options:

• This microorganism will make a fine weapon.
  • Gain modifier: Killer Microorganism
• All-Devouring Microorganism? Meet a your macro match.
  Available only if Requires origin: Evolutionary Predators.
  • Gain modifier: Killer Microorganism
• Quarantine the planet, allowing only careful study.
  • Society: +None to None
  • Add deposit: +8