Great A'Tuin

In Terry Pratchett's Discworld novels, Great A'Tuin is the giant star turtle who travels through space, carrying the four giant elephants (named Berilia, Tubul, Great T'Phon, and Jerakeen) who in turn carry the Discworld. A member of the species Chelys galactica, A'Tuin is the only turtle to ever feature on the Hertzsprung-Russell diagram. The idea of a turtle-carrying-elephant-carrying world is Indo-European; see for instance The King and I and Brewer's Dictionary of Phrase and Fable.

Great A'Tuin's sex is unknown, but is the subject of much speculation by some of the Disc's finest scientific minds - in an analogy to astrophysicists, specialists in this field are called astrochelonians.The sex of The World Turtle is pivotal in proving or disproving a number of conflicting theories about the destination of "Great A'Tuin's" journey through the cosmos. If (as one popular theory states) "Great A'Tuin" is moving to his (or her) mating grounds, then at the point of mating might the civilisations of the Disc be crushed or simply slide off? Attempts by telepaths to learn more about Great A'Tuin's intents have not met with much success, because they did not realise that its brain functions on a near-geological timescale.

Physically, it is not the prettiest sight. Its shell is frosted with frozen methane, pitted with meteor craters, and scoured with asteroidal dust. Its eyes are amazing and entrancing, like ancient seas, crusted with rheum. Its brain is huge and slow moving, with thoughts inching across it like glaciers. Great A'Tuin is the only creature in the universe who knows exactly where it is going.

Following the events in The Light Fantastic, Great A'Tuin attended the hatching of eight baby turtles, each with four baby elephants and a tiny Discworld of their own. They have since gone off on their own journeys.