 Steno who, like almost all 17th century natural philosophers, believed that the earth was only a few thousand years old, resorted to the Biblical flood as a possible explanation for fossils of marine organisms that were far from the sea.Despite the considerable influence of "Forerunner", naturalists such as Martin Lister (1638–1712) and John Ray (1627–1705) continued to question the organic origin of some fossils.They were particularly concerned about objects such as fossil Ammonites, which Hooke claimed were organic in origin, that did not resemble any known living species.