(uncatalogued) The holes in this Gryphaeid oyster were left behind by a boring sponge. Boring organisms have the ability to dissolve calcareous shell which allows them to encrust other living and dead organisms.
(DSM# FK313) Extinct genus - This cephalopod genus was able to survive the K-Pg extinction at the end of the Cretaceous only to go extinct during the Miocene period.
(no DSM#) Extinct species - This oyster that is extremely common in the Late Cretaceous strata of North Mississippi. Sometimes you can find these creatures encrusting other organisms.
Exogyra costata are commonly found in the Cretaceous strata in northeast Mississippi. This example from the Dunn-Seiler Museum shows damage to the growth lines that were repaired as the creature grew.