The Tarcodian Invasion
When the Ancestral Race ascended from Ritjes, the ones left behind had weak, if any energy usage at all. Society could only survive through Dark Matter's fuel, but for the most part were unable to produce the outward expulsion of the energy. Only a slight few select people could still harness the power. During the first millennium of rebuilding, Ritjes' skies exploded in a rain of falling stars. These were not stars, but mechanical monsters, the Tarcodi, and for the next thousands of years the planet would fall victim to these creatures.
They came in various sizes ranging from towering a gargantuan to the size of a tiny fly. Some variations of bio-machine even travel underground. All of them share the same characteristics: they can respire to an extent; their outer skeleton is a dark green not unlike the Ritjes atmosphere and wires can be seen coursing through their bodies. When the bio-machines bleed, it glows neon green. Their blood is actually a coolant to them, but a highly toxic acid to the rest of the planet.
All variants of Tarcodi come with a mechanism to capture prey under many numerous methods. These machines can also infect other beings given enough time in contact. Tarcodi are enveloped in Dark Matter energy, they run off of it, so likewise anyone who comes in close contact with them for prolonged moments do develop the eye rims. The machines are in fact the messengers of the original Ancestral Race. They communicate with one another and are controlled through their brainwaves – but to any normal person it would only sound like high-pitched, garbled noises and static. All bio-machines share the same goal – to capture the people of Ritjes and harvest their energy. They then send that energy to the Ancestral hive mind in space.
For the next thousands of years, the Ritjessians became a victim to these creatures. As the Tarcodi crashed on to the surface, they destroyed what was left of the cities that were being rebuilt. Society had no choice but to move life underground knowing that they were not safe even from the ones that lurked below. They salvaged what knowledge they could and started over. As time progressed, the bio-machines above ground assembled bases consisting of spherical grids of hexagons around the planet. The hexagons were actually giant tunnels of tubes that allowed for quick travel around the planet. A central bio-machine tower rested at each point where the grind lines intersected.