Nicolaus Steno. Portrait of Nicolaus Steno (1638- 86), Danish anatomist and geologist. Steno (born Niels Stensen) discovered Steno's duct in the parotid salivary gland and showed that muscles are made of fibres. He showed that many creatures have a pineal gland which closely resembles that of humans, thus challenging the belief that this gland was the location of the human soul. As a geologist, Steno showed that angle formed by the corresponding faces is always the same for each particular type of crystal (Steno's Law). He also examined fossils and suggested that they were the remains of ancient animals. Steno drew the earliest geological sections to show rock strata.