Shield Turtle
From Record Of Fantasy Adventure Venture
A giant turtle, also called the Aspidochelone, that, when sleeping, resembles an island. It's craggy back looks like a mountain range.
When Alexander the Great was in India, barbarian women on shore pointed out an island in the middle of the ocean that was supposed to have a great king buried in it. Alexander's friends went to take a look, and the Turtle woke up and dove under the waves, killing all those who were on it at the time.
See also Ikulu's List.