... or spectral anything, for that matter. These are just massive copouts, right? They're basically skinless 3D models, polygons without textures.
For my money, however, they could be the funkiest form of mount or pet if, every couple of minutes, they crackled into one of their corporeal forms, just for a few seconds, before fading back to spectral nothingness.
Anyway, that's all I have to say about that.