fossils of a creature bearing a striking similarity to depictions of nessie have been found in a 19th century collection .
it is thought the fossil was found in cromarty and would have once lived in a freshwater lake between 542 million years ago to 251 million years ago .
researchers have revealed that pterichthyoides milleri - or ` pessie ' - lived on the bottom of the lakes that would later become loch ness .