530-million-year-old fossil contains world's oldest known eye

Inside a fossil that’s 530 million years old was an even greater discovery -- the world’s oldest eye.

The eye comes from an extinct sea creature.

It is an early form of the compound eye, which is now found in crabs, bees, and other modern animals.

The fossil was discovered in Estonia by researchers, including University of Edinburgh professor Euan Clarkson.

While the eye does not have a lens, Clarkson says it shows that compound eyes’ structure and function have "barely changed in half a billion years."