Trilobite Fossils!

The fossil in the image appears to be a trilobite, specifically a cast or mold of its exoskeleton. Trilobites are extinct marine arthropods that lived from the Cambrian to the Permian periods (about 521 to 252 million years ago). The distinctive features in the image include the segmented body structure and the curved, ribbed patterns, which are characteristic of a trilobite's cephalon (head), thorax, and pygidium (tail). The white lines highlight the sutures and segments, which are typical in trilobite fossils, especially in molds where the original shell material has dissolved, leaving an impression in the surrounding rock.
The shape and segmentation suggest it could belong to a genus like Phacops or Calymene, which are common trilobites with rounded cephala and well-defined thoracic segments. However, identifying the exact genus or species would require more details, such as the number of thoracic segments or the specific geological context of where it was found. Since this appears to be a mold rather than the actual exoskeleton, it’s likely the trilobite itself dissolved over time, leaving this impression in the sediment.
Given that the previous fossils you showed were tabulate corals, which are also from the Paleozoic era, it’s possible this trilobite comes from a similar time period, perhaps the Devonian, where both trilobites and tabulate corals were prevalent.