Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths of over 9,000 metres (30,000 ft).
Edwardsville is an unincorporated community in Georgetown Township, Floyd County, Indiana. The Duncan Tunnel is located at Edwardsville.
The Devonian Scherr Formation is a mapped bedrock unit in Pennsylvania, Maryland, Virginia and West Virginia.
The Rockwell Formation is a late Devonian and early Mississippian mapped bedrock unit in West Virginia, Maryland, and Pennsylvania, in the United States.
The Fayetteville Shale is a geologic formation of Mississippian age composed of tight shale within the Arkoma Basin of Arkansas and Oklahoma. It is named for the city of Fayetteville, Arkansas, and requires hydraulic fracturing to release the natural gas contained within.
The Brassfield Formation, named by A.F. Foerste in 1906, is a limestone and dolomite formation exposed in Arkansas, Ohio, Kentucky, Indiana, Tennessee and West Virginia in the United States. It is Early Silurian in age and well known for its abundant echinoderms, corals and stromatoporoids. In Ohio, where the unit has escaped dolomitization, the Brassfield is an encrinite biosparite with numerous crinoid species.
Agaricocrinus americanus, also known as the mushroom crinoid or American crinoid, is a species of extinct crinoid. Its fossils can be found in the U.S. states of Indiana, Tennessee and Kentucky. They date back to the Lower Mississippian, about 345 million years ago.
The Edwardsville Formation is a geological structure in the Borden Group, of the Lower Mississippian sub system,. Crinoids fossils can be found in the formation.
The Bluefield Formation is a geologic formation in West Virginia. It preserves fossils dating back to the Mississippian subperiod of the Carboniferous period. Sediments of this age formed along a large marine basin lying in the region of what is now the Appalachian Plateau. The Bluefield Formation is the lowest section of the primarily siliciclastic Mauch Chunk Group, underlying the Stony Gap Sandstone Member of the Hinton Formation and overlying the limestone-rich Greenbrier Group.
The Chattanooga Shale is a geological formation in Alabama, Arkansas, Georgia, Kansas, Kentucky, Missouri and Tennessee. It preserves conodont fossils dating to the Devonian period. It occurs mostly as a subsurface geologic formation composed of layers of shale. It is located in East Tennessee and also extends into southeastern Kentucky, northwestern Georgia, and northern Alabama. This part of Alabama is part of the Black Warrior Basin.
The Bloyd Formation, or Bloyd Shale, is a geologic formation in Arkansas. It preserves fossils dating back to the Carboniferous period.
The Lake Valley Limestone is a geologic formation widely exposed in southwestern New Mexico. It preserves fossils dating back to the lower to middle Mississippian.
The Sandia Formation is a geologic formation in New Mexico, United States. Its fossil assemblage is characteristic of the early Pennsylvanian.
The Virgin Formation is a geologic formation in Utah. It preserves fossils dating back to the Triassic period.
The Madera Group is a group of geologic formations in northern New Mexico. Its fossil assemblage dates the formation to the middle to late Pennsylvanian period.
The Verulam Formation is a geologic formation and Lagerstätte in Ontario, Canada. It preserves fossils dating back to the Katian stage of the Ordovician period, or Shermanian to Chatfieldian in the regional stratigraphy.
Onychocrinus is an extinct genus of crinoids.
The Maysville roadcut, located in northeastern Kentucky, features upper Ordovician rock and fossils. Maysville is located in Mason County, Kentucky, and contains a large roadcut along U.S. Route 68. The cut was human-made in the 1950s and consists of rock that is roughly 450 million years old. Maysville provides an opportunity to observe the stratigraphy of the formations present of the Ordovician time period.
The Pope Mega Group is a geologic unit found in the Illinois Basin of southern Illinois, southwestern Indiana, and western Kentucky. In Indiana and Kentucky its equitant is the Buffalo Wallow Group. This unit grades from sandstones at its base into mix of limestones and sandstone and then a shale at its top. In Southern Illinois oil wells are drilled into the Tar Springs formation.
United States 
