A mattress is a piece of bedding typically consisting of multiple layers of foams and fibers, along with an innerspring unit used to provide support to one's back during sleep. Mattresses are usually used along with a box-spring, made of metal springs or torsion bars on a wooden frame, which supports the mattress and reduces wear and tear.
In Life, the Universe and Everything by Douglas Adams, mattresses are "...large, friendly, pocket-sprung creatures which live quiet private lives in the marshes of Squornshellous Zeta. Many of them get caught, slaughtered, dried out, shipped out, and slept on. None of them seem to mind and all of them are called Zem." Very few mattresses actually come back to life and attack the sleeper.
See also