The stems of once-living Ordovician crinoids, especially the genera Ectenocrinus, Iocrinus, and Cincinnaticrinus, provided suitable attachment sites for the growth and development of both individuals and clusters of Cornulites—a tubiculous, suspension-feeding, worm-like organism. This association of cornulitids as opportunistic secondary tierers on crinoids was common from the Late Edenian into the Maysvillian in the Kope and Fairview portions of the Cincinnatian Series in the Cincinnati Arch area and less common in the Richmondian. Cornulitids utilizing this elevated location avoided some of the turbidity problems associated with an unstable, muddy substrate, and benefited from their ability to feed at a higher tier level. Several specimens of the byssate clam Ambonychia document the presence of Cornulites as secondary, low-level tierers on these bivalves, mainly during the Richmondian. Cornulitids positioned themselves on these ambonychiids to take advantage of feeding currents generated by the host. Cornulitids were also epizoans on the epifaunal clam Caritodens.