Warnowiids are a family of single-celled marine protist. These unicellular eukaryotes have an organelle eye – an ocelloid – that is used to catch prey and avoid predators. An ocelloid can even detect polarized light.
Ocelloids consist of subcellular components which together resemble the camera-type eyes of some animals. It’s an amazingly complex structure for a single-celled organism to have evolved. ~ Canadian evolutionary biologist Gregory Gavelis
Warnowiid eyes are so extraordinary that no one believed German zoologist Oscar Hertwig for nearly a century after he first described them in 1884. But then, it is hard to explain how a unicellular organism can see when it has no brain nor even nerves.
How is the image processed by a single cell? It’s very difficult to wrap your mind around. ~ Canadian marine cytologist Brian Leander