The fossil known as 'Pohlsepia mazonensis', once hailed as the world's oldest octopus at approximately 300 million years old, has been reclassified as a nautiloid due to new research. Discovered at the Mazon Creek site in Illinois, USA, this fossil was believed to have characteristics similar to modern octopuses, including eight tentacles and an ink sac. However, recent analyses using advanced synchrotron imaging revealed rows of tiny teeth inconsistent with octopus anatomy. Lead researcher Thomas Clements from the University of Reading stated that the fossil's decay had obscured key features, leading to its misidentification. This revelation suggests that true octopuses likely evolved much later, during the Jurassic period, rather than existing hundreds of millions of years earlier as previously thought.