A mostly complete trilobite from the lower Cambrian Latham Shale, California--a specimen I did not collect, by the way. The image is courtesy a specific web page. Called scientifically Mesonacis fremonti (formerly genus Olenellus).

The Marble Mountains trilobite locality presently lies within Mojave Trails National Monument (officially authorized and established on February 12, 2016), where the BLM (Bureau of Land Management) continues to allow the casual collection of reasonable amounts of common invertebrate fossils--a designation that here includes trilobites; for fossil sites situated on private property, visitors must secure explicit permission from the land owners.