The Expanoid ship was a massive spacecraft command center used by the Expanoids.
Television series[]
If the word of the Expanoid leader 4 of 27 are to believed, it presumably came a distant future much like the Expanoids themselves, where technology had run rampant to the detriment of humanity.
The Expanoids eventually located the boys from the Dwarf, bartering from them the Casket of Cronus (by a returning a briefly kidnapped Arnold Rimmer) which they then used along with their massive spaceship to create a time hole to Earth.
The Expanoid ship was not seen again, but presumably destroyed on Twentica along with the Expanoids when the Resistance Bunnies turned their own EMP weapons against them. (Twentica, Series XI)
Video game[]
The Expanoid ship has a much more expanded role in Red Dwarf XI: The Game, where Starbug has a shootout with it in space, and Rimmer is forced to escape the ship from inside with a bazookoid.
