A handful of theories attempting to solve the mystery
  1. Sentient mass of cockroaches wearing a human skin-suit
  2. Decaying flesh over solid metal endoskeleton. The T-700 was a complete failure in the field, so Skynet sent him back in time to avoid questions and creep everyone the fuck out with his glassy eyed stare.
  3. Herald of Cthulu?
  4. Someone is secretly filming a Weekend At Bernie's straight-to-DVD sequel nobody asked for.