Lion Turtle form the univers of avatar the last airbender :

The lion turtle is a chimerical hybrid of a lion and a turtle and is the largest known animal in the World of Avatar. According to the aye-aye spirit, dozens of specimens lived during Avatar Wan's time and, as the protectors of mankind, they carried human cities on their backs. Individual lion turtles showed affinity for a specific element, as indicated by the symbol on their forehead and possessed the ability to grant humans the power to control a specific bending art.

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NEW UPDATES : 03/September/2014
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-Completely Rebuilding for a news size, this second version is the double than the first version
length: 415 block
height: 126 block
width: 231 block
-Turtles are hollow inside and has a bedrock layer !
see the news screeshots !!!
Work in progress !!!!!!!