A spaceborne construct created by Doctor Robotnik. It is armed with a powerful death ray weapon that can devastate entire zones. (The name 'Egg Satellite' is unofficial as it was never named in the comic, but it is egg-shaped. Not to be confused with the Death Egg.)
Race Against Time
In STC #11's Sonic story Time Racer, Sonic was lured to the far side of Mobius by Robotnik, who had kidnapped Tails and imprisoned him in a castle in a zone made of fiery pits. With half the world between Sonic and the Emerald Hill Zone, Robotnik activated his Egg Satellite's death ray in order to annihilate Emerald Hill. The ray took five seconds to charge up, which should have been far too little time for Sonic to make it back. By some miracle, however, Sonic was able to reach unheard-of speeds and return home in time. He headed for the beach and used his speed to fuse the sand into glass, creating a giant mirror. Sonic used the mirror to reflect the Egg Satellite's beam back into space and destroy the satellite completely. Emerald Hill suffered no casualties and minimal damage.
Season Of Goodwill
In the STC #93 story Season of Goodwill, Robotnik has built another satellite much like the first one. To reaffirm his authority to the people of Mobius (and to generally just ruin Christmas), Robotnik plans to use the satellite's heat ray to melt the snow in the Happy Valley Zone and flood the region, destroying everyone's homes. His plan is interrupted by the sudden appearance of Father Christmas, who urges Robotnik not to use the satellite and gain peace of mind. Robotnik refuses Santa's offer but cannot use the satellite, for Shortfuse flies into orbit and destroys it.