[MargaretR]

All sentient beings have souls which are different 'energy' inhabiting the physical matter body. This soul energy is indestructable, survives physical death, and has/is conciousness.

Consider this - If the physical 'us' is energy vibrating at a low enough wavelength to be detected by our senses, it is possible for other life forms to vibrate at a different frequency and alter it at their will (so appear and disappear).