A mattress is a creature that is, more or less, a living mattress. These creatures live in the marshes of Sqornshellous Zeta, a very still and quiet planet, much like the lives of the mattresses. These mattresses are another of the objects not manufactured any more, since it is easier to catch and kill these living matresses. However, they are fairly stupid, and do not seem to mind. They are also all named Zem.