The Eye!

Tina Sakha (from Biol 105) shares this video about the evolution of the eye. Here's her summary: The Eye is designed to create images by focusing light into the retina, and sending the signal to the brain. 540 million years ago, the eye had nothing more than photoreceptive patches. It becomes concave but there is very little directionality. In the beginning the eye wasn't concave enough, though it evolved into more concave shape as time passed. Pinhole camera eyes allow for greater directionality. The cornea develops over the eye, as well as a fluid called humour to protect the eye from damage. A lens develops to focus the light, and providing even greater directionality.

If you are in the habit of watching the History Channel (and who isn't?) you might have caught their recent hour-long treatment of the evolution of the eye, which opened their ongoing series "Evolve". Recent episodes of the series are available for viewing online on their website, and you can find older ones, including the one on the eye on iTunes.