This Eucalyptocrinus crassus crinoid calyx bears the remnants of a Crania sp. brachiopod. These brachopods existed in the Middle Silurian Period and their fossils can found in the Waldron Shale of Indiana. These brachiopods tended to attach to dead crinoids and brachiopods.
The next picture is an illustration of four holdfasts of the Crania siluriana brachiopod. The illustration shown was drawn by J.C. McConnell and can be found on Plate 21, Figure 6 of the Indiana Department of Geology and Natural History (Eleventh Annual Report) John Collett, State Geologist, 1881.
Last picture is of the first fossil shown but showing the attached matrix.
