There are no trilobites in the world today, though at one time they were the most plentiful animals on earth; At that time they were also the largest and most advanced of all animals. The Age of the Trilobites lasted more than 100 million years. Their heyday was the Cambrian Period of earth's history, a chapter which closed. some 440 million years ago.
The name trilobite means having three lobes or sections, The typical trilobite was a crawling animal with head, thorax, and abdomen. His back was protected with a crust or shell divided into segments. The legs and inside of the body seem to have been soft and unprotected, for we rarely find these parts of the trilobite preserved as fossils. Most of our information about the total trilobite body comes from fossil impressions in ancient rocks.
It is evident from the rocks where we find the remains of the trilobites that they were sea creatures. As far as we know, none of them ever tackled life on the land. Some may have lived in the darkness of the deep ocean. For some of the fossils indicate that certain trilobites were sightless.
The dwellers in deep water, however, seem to have been the exceptions. From what we can gather, it seems that the average trilobite enjoyed life on the floors of the ancient, fresh water seas. He crawled along in the sand and mud, grubbing for algae and scraps of decaying material. He may even have been able to take a few clumsy swimming strokes.
The smallest of the trilobites were but a fraction of an inch long. The largest were more than 27 inches long. Simple as they were, these creatures tried to improve themselves. At the start of their long reign, every trilobite was a flat, unjointed animal. Toward the end of their reign, some of them had learned to coil themselves around. They had learned how to protect their soft underparts from attack.
In the Age of the Trilobites, there were no fish and no backboned animals of any sort. That 27‑inch trilobite was the grandest animal in the world. Simple backboned animals appeared towards the end. of the trilobite reign. And again, it seems, the trilobites tried. to change themselves to keep pace with things.
Though the true trilobites disappeared hundreds of millions of years ago, some of their descendants managed to survive. These offspring were so different that they cannot be called trilobites, The experts believe that they are. the scorpions, the crustaceans, the millipedes, and even the insects. These descendants of the trilobites, unlike their ancestors,, are not the most advanced animals in the world. But they have a large and very secure place in the animal world.