When you build a ship in creative mode and blueprint mode and then cancel it. A ghost ship is created (since the game remembers blueprint changes for convenience). When you Ctrl+A to select everything on the map the ship appears as invisible control room.
On a side note when I created a composite ship and then un-pause, it goes into a more forced spin than before. While doing so they game lags extremely. I know this was made to resolve on-top and entangled collision.
