Eyes

Crystal eyes

Trilobites saw the world through lenses of calcite, a mineral.

How this site works. Every fact is in our own words and linked to its source, beside it. Where good sources disagree, we show each version in a “Sources differ” box.

Trilobite eyes were made of calcite, a crystal: the NHM says no other animal is known to have had that before or since. NHM

Fortey says other arthropods have soft eyes, made of cuticle like the rest of the body. NHM

Most had compound eyes made of many separate lenses, though blind forms are known. BGS

Most were stacks of calcite prisms pointing in slightly different directions; more prisms probably meant better eyesight. NHM

Species had anything from one to several thousand lenses. NHM

Different eyes, different lives

Phacops had more complex lenses, and may have been able to see an object clearly and judge how far away it was. BGS

Phacops eyes had drop-shaped lenses rather than hexagonal ones. NHM

Some big, curved eyes gave a view forwards, backwards, sideways, up and even down. BGS

Some with giant bulging eyes were probably open-ocean swimmers watching for prey. NHM

Erbenochile had tall, tower-like eyes that could probably scan for prey at a distance. NHM

Asaphus kowalewskii had eyes on stalks. NHM

One species of Cyclopyge had eyes fused into one large ‘super eye’. NHM

Others had no eyes at all, and may have burrowed in mud or lived deep in dark water. NHM

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