Doodle day is illustrated in a style where there are six stacks of geological layers with a variety of fossils and a layer of green in the topmost layer.
Scientists from Denmark started studying medicine at the University of Leiden in the Netherlands at a young age (20 years). Then he went stdui anatomy in Italy, by generating a neighbor tooth shark research.
He later discovered that the tooth shark has a certain resemblance to the objects of rock. From there he found the concept of fossils and identify them as living organisms.
Steno also expressed the theory that the oldest rocks are old rocks found in the deepest soil layers, except if there is a changing structure. Thus, to determine the age of fossils, can be estimated from the soil layer where the fossil was found.
Major projects and famous who've done Steno was Anatomical Observations (1662), Elementorum Myologiae Specimen, Seu Musculi geometrica descriptio (1667), Concerning Solids Naturally Contained within Solids (1669), Elementary Mylogical specimens (1669), and Discours de M. Stenon sur L'Anatomie du Cerveau (1669).