Dimly illuminated and very very swamp-intensive, Squornshellous Zeta is the source of almost all the Galaxy's . Said mattresses (all of which are called ) spend most of their time flolloping, globbering, volluing, and vooning. Said activities make the planet a favourite destination of etymologists. The Zem themselves remain a foot tall, until they are freeze-dryed and cleaned, and made into mattress-size corpses (which are promptly used as mattresses). It is a process which, strangely enough, they don't seem to mind at all. Very few mattresses have ever come back to life again.
Marvin the Paranoid Android was invited to the planet to give a speech marking the opening of a giant new bridge intended to revive the economy of the Squornshellous System, said bridge also costing the total sum of the economy of the entire planet to create and the whole ceremony ended in tears. Marvin was plugged into the bridge and the whole cyberstructure instantly folded itself up and collapsed (presumably after being directly exposed to Marvin's chronically depressed view of the Universe). Marvin was left stranded in the swamp with only the mattresses to talk to, until robots from Krikkit stole his leg, and then the rest of him.