A study from Lund University shows that a one-eyed creature living 600 million years ago is among our oldest ancestors and gave rise to modern eyes. According to researcher Dan-E Nilsson, this cyclops-like ancestor was a worm-like organism that lived as a burrowing filter feeder, extracting plankton from seawater. Because it remained stationary, it did not need paired eyes for movement, instead retaining light-sensitive cells on its head to monitor circadian rhythms and orientation.
The research explains why human eyes differ from those of other animals, tracing their evolution from this ancient lineage.