For your consideration, a collection of 5 trilobite fossils. Trilobites date back to the Cambrian Period and were among the first multicellular animals to live in the ocean. Thousands of species have been identified, leading some to call trilobites the beetles of the Paleozoic. These five fossils are of two different types and sizes. Each of the fossils present nicely in the rock in which it formed. The largest specimen measures 3 1/4" x 4".