That would be Bishop Nicolas Steno. Google’s description of him:
Google revealed its latest homescreen Google Doodle today, this time commemorating the birth of Nicolas Steno, a 17th century researcher and bishop who straddled the worlds of science and religion. Born on this day, all the way back in 1683, Steno studied medicine at the University of Copenhagen, and then set as his challenge to research as much of life as possible, rather than simply accepting what had been written in a book.
Before he died at the age of 48, Steno had discovered a new piece of animal anatomy, correctly identified the heart as simply another muscle in the body, created what have become three core rules of geology and identified a fundamental rule of angles in crystals. Steno also identified the correct source and preservation of fossils, which some had believed were fallen objects from space.
The blog Catholicism Pure and Simple has even more.