Trilobites are the single most diverse group of animals preserved in the fossil record.
Trilobites were the first animals to have eyes.
Human beings have one lens in each eye, but some trilobites had as many as 20,000.
Eight orders of Trilobites are recognized, into which 15,000+ species are classified.
Trilobites appeared 570 million years ago and are the ancestors of today’s shrimps and lobsters.
The last of the trilobites disappeared about 230 million years ago.
The embryology of trilobites is unknown, but after hatching and development of a hard exoskeleton (which presumably occurred soon after hatching) they molted their exoskeletons as they grew, as all arthropods today, leaving a record of their developmental stages.