Jurassic. Holzmaden Black Shale Formation. Holzmaden, Germany. Sea lilies (crinoids) – relatives of starfish and other echinoderms – filter small food items from the water with their long, jointed arms. Nearly all sea lilies, living and extinct, lived near the sea bottom. The Holzmaden ocean was special: Long-stemmed sea lilies attached themselves to floating logs and let their bodies and feeding arms hang down into the still water. Some grew stems up to 50 feet long. Apparently the log that this specimen was attached to became water-logged and sank to the ocean depths, dragging the crinoid to its death. The low oxygen environment in the ocean depths helped to preserve this beautiful piece.