Turtle

Turtles are essentially robots. They will be in the 1.3 update. They run on TurtleOS. In 1.3, it has been hypothesized by the creator that they may only be able to place blocks, break them, and use a pick-axe as tools for the base 1.3. They can be coded to place blocks, or move. Their programs are stored on floppy disks.

Fuel:

Turtles are equipped with a state of the art Waste->Fuel quantum ionizing engine. Meaning no need for extra fuel/charging. The initial redstone in the recipe for the computer which is then used in its recipe, Is the "start up" fuel, It's emmisions and waste are then converted back into fuel, By the ionizer making a huge circle of Waste->Fuel->Waste->Fuel... Therefore there is no need for external powering.