This series of pictures are of two fossil specimens. The strophodonta brachiopod shell fragments had colonies of Aulopora growing on them. The coral was exposed with the help of Oxalic acid. The fossils are from the Devonian Period and appear be from the Silica Shale.
Learn more about the Aulopora coral at this Wooster Geologist blog posting from January 2011: CLICK HERE TO READ.
Thanks to Dave at Views of the Mahantango blog for these specimens and the cleaning work performed on them. You can see some of his Aulopora finds HERE.