In the Great Underground Empire turtles can grow to enormous size and have incredible longevity.

One such turtle, was once the favored pet of King Mumbo II in 619 GUE, who determined the measurement of the bloit during the king's reign. About 881 GUE, a wizard cast a spell on him, magically enamelling his shell with all the colors of the rainbow. He was particularly proud of his new shell, and henceforce, this turtle was the father of a new breed of "rainbow turtles" which began to populate the Southland shores. In 956 GUE, this turtle resided on the beach near Largoneth, and helped an enchanter defeat the warlock Krill.

For some unknown reason, by the eighth century, many people believed that the world rested on the back of a giant turtle. The most famous of the treatise of Leonard Flathead disproved this hoary myth, claiming to instead prove that the world actually rested on the head of an enormous troll. This theory too has since be proven false.