Compound eye of Dragonfly
A compound eye is a visual organ found in certain arthropods (some insects and crustaceans). The compound eye consists of 12-1000 ommatidia, little dark/bright sensors. The image percepted by the arthropod is "recalculated" from the numerous ommatidia which point in slightly different directions. In contrast to other eye types, there is no central lens or retina. Though the resulting image is poor in resolution, it can detect quick movments and, in some cases, the polarization of light.
The body of the brittlestar species Ophiocoma wendtii is covered with ommatidia, turning its whole skin into a compound eye.