Educational opportunities provided by a resedimented and bioeroded bivalve steinkern from the Cenozoic of western Florida, USA

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A venerid (Mercenaria?) bivalve fossil, recently collected as an allochthonous bioclast from a beach in Florida, USA, presents an opportunity to discuss aspects of paleontology and sedimentology that may be useful to educators involved in the geological and/or biological sciences. The specimen, which was transported to the shore following a storm event, is preserved as an internal mold (steinkern) that is completely penetrated by the bioerosional ichnogenus Gastrochaenolites. This otherwise inconspicuous fossil records evidence of a surprisingly complicated history, including shell burial and infilling, lithification of infilling sediment, dissolution of shell, incorporation into a lithified bioclastic sedimentary layer, boring through the layer by a different bivalve, erosion by storm currents, and transportation onto the beach. The occurrence of this specimen as an allochthonous pebble illustrates an instance in which trace fossils can be transported and highlights the significance of storm events in facilitating resedimentation of bioclastic material in carbonate settings.