Answer :
Well Trilobites first appeared about 521 MILLION years ago, which is around the Early Cambrian Period. Trilobites were early anthropods that lived in the Earth's sea. They had hard-shelled bodies, and their bodies were composed of multiple body segments and jointed legs. Trilobites are made up of 3 main body parts, the Cephalon (the head), a segmented Thorax, and a Pygidium (the tail). Hope I helped!
The trilobites were found in the Cambrian Period of the Paleozoic Era. They had a head, tail and a body. They looked like little hard shelled insects.