This was not a particularly large metal planet.
The metal planet's location was just 0.1 light-years away from the edge of the Galactic Center Dome.
It did not exist in isolation, but as part of an immensely massive system of unnaturally made objects.
It could be seen as a component of a giant machine.
This machine was named by human scholars as the Galactic Center Iron Wall Chain Formation, covering the outside of the Galactic Center Dome, composed of countless artificial planets.
In the Galactic Center within the Dome, countless stars constantly emit massive amounts of light, providing the space with an inexhaustible supply of light energy.
After failing to break through the human defenses by dispatching three large fleets at once, and entering a state of deadlock and tension, the Compound-Eyed Observer spent a large population, resources, and 20 years of time, to build this chain array outside the Galactic Center Dome.