The Ornithary is a space-worthy pirate ship used by the dead.
In the legends of many races, the Ornithary is renowned for carrying dead spirits to the Realm of the Dead. After the coming of Tetradox to the realm, his presence somehow altered what can be taken as physics there and outside help was needed to restore it. Once Zelgo Furiox brought back Skull, the Captain of the Dead, the crew of the Ornithary returned and it bore them to battle.
The ship had 4 pairs of large wings coming out of the sides, that enabled it to fly, and maneuver, along with a sail in the middle. There were no shields or life support systems of any kind on the ship because the need for oxygen and the concept of dying were both non-existant in the Realm of the Dead. It was semi-sentient, much like the Radiant or the Tournan Hive Ship or any of the multitude of Silverwood's cars.