Holochroal eye
Encyclopedia
Holochroal eyes are compound eyes with a many (sometimes over 15,000) tiny lenses (30-100μm, rarely larger). They are the oldest and most widespread type of trilobite
eye, and found in all orders of trilobite
from the Cambrian to the Permian periods. Lenses show hexagonal close packing, and a single corneal membrane
covered all lenses. Unlike most modern arthropods, these eyes were not covered by the white layer known as the sclera.
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
eye, and found in all orders of trilobite
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
from the Cambrian to the Permian periods. Lenses show hexagonal close packing, and a single corneal membrane
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
covered all lenses. Unlike most modern arthropods, these eyes were not covered by the white layer known as the sclera.