Nanobots

The nanobots are a swarm intelligence inhabiting the Sayaiban system originally created by the Korath. They are guarded by an Archon named "Watchful Gravetender", which will contact you the first time you enter the system. The swarm is being preserved as a living memorial to the Korath in case they drive themselves extinct. The Archon claims that the nanobot swarm is the "last of their great abominations."
In game, the nanobots are invisible ships that will attack you and the only way to avoid them is to cloak.