The spacecraft seems to be a triangular prism with a white metal coated floor and a large transparent window on one of its sides for Bubbles to look out of. The spacecraft is equipped with an old-style bathroom.
The glass window is the only part that can be seen outside of the spacecraft.
Role in movie
While SpongeBob and Plankton time travel in their time machine, they accidentally arrive at Bubbles' spacecraft in the "middle of space." While there, Bubbles asks them to watch the cosmos for him so he can take a bathroom break.
During that time, Saturn and Jupiter crash into each other, which makes Bubbles angry and start shooting laser beams at them.
In one scene, when SpongeBob and Plankton are thrown in the air after almost being zapped by Bubble's laser, bubbles are shown, even though this is not located in the ocean.
Sea creatures like SpongeBob and Plankton are able to breathe in this spacecraft.
According to storyboards from a scrapped storyline of The SpongeBob Movie: Sponge on the Run, Bubbles originally had a dolphin-shaped spaceship after the event of the previous movie. SpongeBob, Patrick, Squidward, and Sandy were supposed to break in at some point.