Fossils

Finally, something in these halter-skeleton layers of mind-bending age that I tracked down: Leptaena genus brachiopods. “Common in limestone that formed on shallow continental shelves” now found in “Ordovician, Silurian, and Devonian strata worldwide” (Chris and Helen Pellant Fossils: A Photographic Field Guide). Over 70 recognized extinct species per Wikipedia: with a more detail on the life-span:  Dariwilian epoch to the Emsian epoch.