Millius Prime served as the Diathim's homeworld and was one of the thousand moons in orbit around the planet Iego. During the Clone Wars conflict, the Confederacy of Independent Systems seized control of the moon, establishing the main control center for a LaserWeb Defense Station there. Later, Jedi Knights Obi-Wan Kenobi and Anakin Skywalker, representing the Galactic Republic, destroyed this installation.
As the largest of the thousand moons orbiting Iego, Millius Prime was an enigmatic celestial body. Iego itself resided in the Outer Rim Territories of the galaxy, specifically in grid square T-7 of the Standard Galactic Grid. When viewed from space, its surface presented a purple mottled appearance, marked by extensive cratering and a generally smooth, rocky landscape.
By 21 BBY of the year, the Confederacy of Independent Systems had taken Millius Prime by force, driving the Diathim, the indigenous inhabitants, away from their native land. Subsequently, the Confederacy integrated the primary node of a LaserWeb Defense Station into the moon's topography. This was designed to prevent departures from Iego, but Jedi Knights Obi-Wan Kenobi and Anakin Skywalker of the Galactic Republic later destroyed it, freeing both the moon and the planet below.
Millius Prime made its debut in "Mystery of a Thousand Moons," which was the eighteenth installment of Star Wars: The Clone Wars' first season. It was originally broadcast on February 13, 2009. The Episode Guide on StarWars.com provided confirmation that the moon housed the Separatists' main laser web node. In 2017, the reference work Star Wars: The Visual Encyclopedia included an image of Millius Prime, using concept art created by Jackson Sze that depicted Iego and its moons.
Another piece of concept art reveals that the "Main Laser Station" embedded within Millius Prime was intentionally designed to resemble the superlaser emitter of the Death Star.