The mattress globbered.
—The main mattress pastime[src]

A mattress (deceased).

Mattresses are friendly, dim-witted, docile creatures capable of speech. They are all called Zem and live in the swamps of Sqornshellous Zeta. Many of them are slaughtered, dried out, and shipped around the galaxy to be slept on by grateful customers, though they do not appear to mind this, one noting that since they are all called Zem they never know which of them have been killed anyway so their concern and grief - "globbering" - is kept to a minimum.

No one really knows what mattresses are meant to gain from life. They live quiet, private lives where they "flollop and vollue" to amuse themselves.

Mattresses make a variety of noises that are not supposed to be able to be made by other lifeforms throughout the galaxy, such as willomies, globbers, flurs, and glurries. Those being only a few examples. Mattresses are also capable of doing things floopily, meaning in a floopy manner.

The book Sqornshellous Swamptalk is a dictionary of mattress vocabulary.