Neptune

Neptune is a location in EBCGD. It is the only location outside of Earth.

FreeSmart
Dr. Eggman wanted to fly to Neptune for some fuel to get to Eggmanland. But the FreeSmart Rocketc Ship crashed into it, and they fused. Kirby's Warp Star flew through Neptune. Later, all were taken back to Earth. Now, it is represented by Neptuneball.