Paleobiology of Kerunia comuta MAYER-EYMAR, 1899 from the Upper Eocene of Egypt

The taxonomic position of Kerunia cornuta is a matter of controversy. It has been classified as a cephalopod, a species of the hydrozoan genus Hyractinia and as a stromatoporoid. Oriented thin sections, serial sectioning and SEM studies reveal a basically hydrozoan microstructure. The characteristic shape of Kerunia is the net result of a complicated symbiotic relationship between a hydrozoan, a hermit crab, and its original home inherited from a gastropod. Functional morphology, associated epibionts, and field observations suggest that Kerunia cornuta lived on shallow marine bottoms.