Reports

Trilobite Eyes: Calcified Lenses in vivo

Science  09 Mar 1973:
Vol. 179, Issue 4077, pp. 1007-1009
DOI: 10.1126/science.179.4077.1007

Abstract

The corneal lenses preserved in the eyes of some of the Paleozoic trilobites (Arthropoda) are constructed of calcite that is crystallographically oriented to behave like glass. The calcareous lenses are capable of forming inverted images over a large depth of field and must have been present in the living trilobites.