Still from this video: https://www.youtube.com/watch?v=2PNXpP17tGc. The "Cave of Hands" is a trope, basically: similar concepts appear in, for example, the 1965 Polanski film "Repulsion", and Jim Henson's "Labyrinth", though in this case I was, eh, inspired by a Dutch comic, "Storm". I like the idea of a living environment, a location with an instinctive will to protect itself. It's a little more intriguing than "Fantasy Dragon Creature #15,646".