Fossil (IMAGE) University of Leicester Caption The fossil of a 300-million-year-old primitive jawless fish -- a lamprey -- about 6 cm in length. The eyes are the two dark circles on the right-hand side and are so well-preserved the retina and lens can be seen in high magnification. Credit Rober Sansom Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.