Just when you think you've got life all figured out... scientists find something that redefines the whole concept.  Ecology Hour hosts Bob Spies and Tim Bray talk with Dr. Karen Lloyd, Professor of Earth Sciences at the University of Southern California, about her research into alien life forms right here on Earth - what she calls "Intraterrestrials" in her new book. Some of these organisms challenge our basic understanding of life: their metabolic processes function so slowly that individuals may live for hundreds of thousands of years. Some of them can breathe Arsenic; others eat methane and produce formaldehyde. Their discovery has created a new and wild frontier in scientific research, and Dr. Lloyd is in the vanguard.