The Mothership orbits the Earth, and was used by Cosmo and Wanda, who were playing a game alongside their godson Timmy Turner, whom was reenacting a Crash Nebula episode.
The spaceship is a gray metal color, and is shaped like a mother pushing a baby carriage (a pun on its name).
In the episode, "Spaced Out", Timmy Turner was reenacting an episode of Crash Nebula he saw on television with Chester and A.J.; his friends playing the role of the aliens, and himself playing as Crash Nebula. Timmy used a magic remote device to call his fairies, who were in the mothership in space. Cosmo and Wanda answered Timmy's distress signal, and Wanda took command as it was the mothership. Cosmo was forced to don a maid outfit, was put on cleaning duty, and was also ordered by Wanda to grant Timmy's wish for more firepower. Cosmo and Wanda poofed back to their goldfish bowl shortly afterward.
The mothership appeared again later in the episode, where Cosmo and Wanda watched it on their wands being destroyed by the Yugopotamians upon their arrival to Earth.