The Bonecrusher is a modified seperatist flagship used by IG-211. It has a modified giant fork-claw to crush incoming fighters or other battle crusiers. It was named after the decepticon Bonecrusher, who had a large fork like claw weapon, and has his head as an emblem on both sides of the hull as well as inside the ship.
The Bonecrusher was given by Grievous to Killer as a gift for his act of courage and his viciousness. It was destroyed when in battle above Coruscant.