Check the listing for details. Rare Arthroacantha carpenteri Fossil Crinoid Silica Shale Devonian Sylvania OH. Condition: Used. Listed at 75.00 USD. The Arthroacantha carpenteri fossil crinoid is a unique and rare collectible piece from the Devonian period, found in the silica shale deposits of Sylvania, Ohio. This ancient echinoderm is preserved in exquisite detail, making it a valuable addition to any collection of fossils or rocks. With its intricate structure and historical significance, this fossil crinoid is a prized possession for collectors and enthusiasts alike.