This image shows what appears to be a Hederella bryozoan and spirobis (palaeoconchus?) that grew on a Cliothyridina sublamellosa brachiopod fossil. Fossils were found in the Glen Dean layer at Grayson County, Kentucky, USA. These creatures existed in the Mississippian Period.
Thanks to Kenny for image.
Corrections: Earlier post listed the brachiopod as a Reticularia setigera and the spelling for spirobis has been adjusted.