Erythro - the planet discovered in the book Nemesis by Isaac Asimov. The planet is apparently barren apart from a covering of micro-organisms. After several people who venture out onto the surface of Erythro are mentally damaged by the experience, the main character in the book, Marlene, is drawn to go out onto the surface. She discovers the reason for the injuries suffered by others is that the planet itself is trying to make telepathic contact with the humans and only her own brain is suitable for communication. The planet is not alive in itself but the micro-organisms covering the planet form the consciousness. Asimov hints in Foundation's Edge that Erythro may be Gaia.