Trilobite Elrathia Fossils in Slate Stone Matrix - Delta Utah Set of 4

Selling 4 pieces as a set. Trilobite Elrathia fossils in slate matrix from Delta Utah. Trilobites are over 500 million years old and from the Cambrian period in the Palaeozoic Era. I collected these myself as an amateur collector. There may be other species of fossils in these specimans, but I am not an expert on identifying them. The slate color is a deep gray / blue that looks different depending on the lighting and background. Each piece of slate contains at least one fossil. the largest piece is 4.75" x 3". The smallest is 1.5" x 2.5". Smoke free home.