Help the ghosts navigate the spirit and living world with their ability to possess objects. Ghosts can pass through walls in the living world, but can't pass through walls in the spirit world. The only way a ghost can pass through a wall in the spirit world is by possessing an object. Ghosts can also collect abilities and apply them to possessed objects. Ghosts can collect stars and enter doors in the spirit world, but must possess an object to collect stars and enter doors in the living world.