Ancyrocrinus spinosus   scale in cms CLASS - Crinoidea ORDER - Cladida FAMILY - Botryocrinidae GENUS/SPECIES - Ancyrocrinus spinosus ROCK UNIT - Jeffersonville Limestone AGE - Middle Devonian (380 million years old) LOCALITY - Great Falls of the Ohio, Jeffersonville, Indiana, USA   Crinoids attached to the sea floor by many different methods. Some coiled their stems or attachment arms (cirri) around other stationery sea floor objects. Others used different styles of specialized anchoring structures or "holdfasts", including those resembling roots, weighted globes and cemented discs. This distinctive holdfast had 4 or 5 back-directed spines similar to a grappling hook. The crinoid would snag this hook-like holdfast on seaweed or other firmly attached crinoids. Such an attachment may have been useful on sea bottoms composed of shifting sediment. These specimens were collected in the 1850s, long before Great Falls of the Ohio became a protected area (State Park and National Wildlife Conservation Area). CU 5495