"Although extinct now, the trilobite nevertheless speaks to us today concerning ingenious design and purposiveness in nature. Unlike the lens of a human eye, which is composed of living, organic tissues, trilobite eyes were composed of inorganic calcite. Consequently, many trilobite lenses have been preserved in the fossil record allowing paleontologists to study them. What they have discovered is truly impressive.
Unlike human eyes which are composed of a single lens, trilobite eyes have a very special double lens design with anywhere from 100 to 15,000 lenses in each eye, depending on the subspecies. This special design allowed the trilobites to see underwater perfectly, without distortion. Implicit knowledge of Abbe’s Sine Law, Fermat’s Principle, and various other principles of optics are inherent in the design of these lenses. They appear to have been carefully designed by a very knowledgeable physicist, and indeed, the creationist would agree---they were!”
(Scott M. Huse, “The Collapse of Evolution, p. 27)