Cuttlefish eyes are among the most developed in the animal kingdom. The way cephalopod eyes develop is fundamentally different from that of vertebrates like humans, but the way they work is rather similar. The similarity between cephalopod and vertebrate eyes is an examples of convergent evolution. Although they cannot see color, they can perceive the polarization of light, which improves their ability to see contrast. They have two spots of concentrated sensor cells on their retina (known as fovea), one to look more forward, and one to look more backwards. The lenses, instead of being reshaped as they are in humans, are instead pulled around by reshaping the entire eye in order to change focus.