Myelodactylus fletcheri, crinoid fossil. Crinoids are marine organisms, most of which have long stalks anchored to the seabed, with five or more feathery arms radiating from a central disc. This is one of the feathery arms of this species. This specimen dates from the Silurian period (440 million years ago), and was discovered in the Wenlock Limestone formation of Dudley, Worcestershire, UK. It is part of the collections held at the Natural History Museum, London, UK.