‘Entobia balls’ in the Medobory Biohermal Complex (Middle Miocene, Badenian; western Ukraine)

Abstract

The peculiarly shaped ‘Entobia balls’, from the Middle Miocene (Badenian) Medobory Biohermal Complex, western Ukraine, are a maze of moulds of clionid sponge borings belonging to the ichnogenus Entobia Bronn. The ichnospecies recognized (Entobia geometrica, E. paradoxa, E. cateniformis, E. laquea) are ascribed to the activity of two extant zoospecies, Cliona vastifica Hancock and C. celata Grant. Their habitat was provided by thick-walled shells of the bivalve Chama gryphoides garmella de Gregorio, the shells of which were drilled through completely. Some small patches of borings are compatible with those of the extant zoospecies Cliona viridis (O.Sschmidt).