If you go to the octopus, and if you're not too squeamish, dissect it. You'll find that it has a camera eye which is remarkable similar to our own. And yet we know that the octopus belongs to an invertebrate group called cephalopod mulluses, evolutionarily very distant indeed from the chordates to which we belong.

The manner in which life constructs itself must be dealing with some other principle which we've failed to identify.

The common ancient ancestor of mulluses and chordates could not possibly have possessed a camera eye, so quite clearly they have evolved independently. The solution has been arrived at by completely different routes.

Simon Conway Morris Quotes