earth

A planet in the Milky Way galaxy. It is the home of unique organizations of energy dependent cells that like to reproduce themselves exponentially through both sexual and asexual reproduction. Many such "organisms" consist of a mouth, an anus, and a stomach system. Other features are numerous and diverse, but all help these animated conglomerations of material in their never ending quest to unsustainably gobble energy-latent objects in their environment while producing an iterated and highly-particular stream of waste products. The planet is named after the original creatures with this body plan, the worm.

A computer built by a race of hyperintelligent pan-dimensional beings to calculate once and for all the Ultimate Question of Life, the Universe, and Everything, to which the answer is 42.

This computer was so large that it was frequently mistaken for a planet - especially by the strange ape-like beings who roamed its surface, totally unaware that they were simply part of a gigantic computer program. And this is very odd, because without that fairly simple and obvious piece of knowledge, nothing that ever happened on the Earth could possibly make the slightest bit of sense.

Sadly however, just before the critical moment of readout, the Earth was unexpectedly demolished by the Vogons to make way - so they claimed - for a new hyperspace bypass, and so all hope of discovering a meaning for life was lost for ever.

Harmless.

Mostly Harmless.
(also: Mostly Harmless)