Creatures that lived about 500 million years ago had complex structures no different from those of today. Fossils that appeared in the Cambrian period have been shocking for scientists, especially for the evolutionists. Because according to the theory of evolution, creatures of that period should have had "primitive" systems, different from the living things of today.
However the complex systems they have like eyes, gills and circulatory system are evidence of the fact that these creatures were not primitive. For example, the trilobites of the Cambrian period had compound eyes with multi-faceted eye lenses as do some insects today. These complexly structured eyes of the trilobites consisted of hundreds of hexagonal lenses forming a structure resembling a honeycomb. This perfect eye structure which appeared 530 million years ago forced evolutionists to express their amazement.
David Raup, an evolutionist professor of geology at Harvard, Rochester, and Chicago Universities, is forced to acknowledge the impossibility of the formation of the trilobite eye by chance saying: "the trilobites 450 million years ago used an optimal design which would require a well trained and imaginative optical engineer to develop today". (David Raup, "Conflicts Between Darwin and Paleontology", Bulletin, Field Museum of Natural History, Vol 50, January 1979, p. 24.)