Microbiota (gut flora) contain between 400 and 800 bacterial species and are usually classified in two divisions: Bacteroidetes and Firmicutes; Clostridium cadaveris are Firmicutes.
In 2003, he, Frank Corsetti and David Pierce published evidence in the Proceedings of the National Academy of Sciences of fossilized microbiota in Cryogenian rocks, a revelation which has cast doubt on the notion of the near elimination of life during potential equatorial glaciation during that period (commonly referred to as Snowball Earth).