Turtle (siege engine)
A turtle is a siege engine used to protect attackers during a siege, similar to the shell of a turtle.
A Storm of Swords
The free folk use a crude turtle to attack the gates leading through the Wall at Castle Black in the battle beneath the Wall. It is described as a "a hull turned upside down and opened fore and aft; a longhall on wheels". The turtle has a rounded top and eight huge wheels with a stout wooden frame underneath and a number of layers of raw mammoth skins on top of sheepskins and pelts. It is eventually destroyed by the men of the Night's Watch, who drop barrels of frozen gravel on it from atop the Wall.