Black Comet

The Black Comet is a celestial object and the mobile homeworld of the Black Arms led by Black Doom. The comet is capable of traversing the galaxy, allowing the Black Arms to attack and consume the populations of worlds they come across. The comet approached Mobius fifty years ago, and Black Doom contacted Professor Gerald Robotnik and aided him with his Project Shadow, with Doom planning to use Shadow the Hedgehog as an agent. The comet departed soon thereafter, and while on its return trip to Mobius the Black Arms ran afoul of the Xorda, another alien race with its own claim to Mobius. The two races began warring, with the Black Comet currently in orbit around the ravaged Argentium. (StH: #169, #170, #171; The Complete Sonic Comic Encyclopedia)