> Wolf "Maybe the Martians are transmitting neural images of red rocks directly into our brains, but we don't have the sense to tell" spirit

This reminds me of a book I used to have called "Lost Race of Mars" about a family who makes an extended visit to Mars because the dad was a scientist and was studying Martian life. Tortoises with eyes that look up as well as the standard forward-facers, cats, etc... well, the kids find a cave where the Old Martians live. The reason they're so hard to find is that they're psychic and can project illusions into humans' minds, so that the opening doesn't appear.

Nyper"Sorry, I don't remember the time frame of the story, the copyright date, or the author's name"old