Symbiosis of genus Hydractinia and in situ hermit crab in Kerunia cornuta Mayer-Eymar, 1899 from the Upper Eocene rocks in northwest Qarun Lake, Fayum area, Egypt

• Published in: Journal of African earth sciences (1994) Vol. 198; p. 104789
• Main Authors: Sayed, Dina M., El-Shazly, Soheir H., Salama, Yasser F., Abd El-Gaied, Ibrahim M., Badawy, Hanan S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2023
• Subjects: Egypt; Fayum; Hermit crab; Hydractinia; Kerunia cornuta; Upper Eocene; Upper Eocene; Hydractinia; Hermit crab; Kerunia cornuta; Fayum; Egypt
• ISSN: 1464-343X; 1879-1956
• DOI: 10.1016/j.jafrearsci.2022.104789

The Upper Eocene rocks (Qasr El-Sagha Formation) at northwestern Qarun Lake, in Fayum depression, revealed numerous abraded and bio-eroded Kerunia cornuta specimens, with calcified hydractinian encrustation. The symbiotic relationship between the encrusted genus Hydractinia and the host gastropod shell is discussed through thin section examination. A report of in situ hermit crab in the host gastropod shell in Kerunia cornuta is documented here for the first time from the Eocene rocks of Egypt. The studied bioerosion structures in Kerunia are attributed to three ichnospecies: Gastrochaenolites lapidicus Kelly and Bromley1984; Gastrochaenolites torpedo Kelly and Bromley1984 and Gastrochaenolites isp. These ichnospecies are related to Trypanites ichnofacies in an offshore environment under storm wave base. The taphonomic processes that affected the Kerunia cornuta specimens are also discussed in this work. The present study indicates that the paleoenvironment prevailed during the deposition of the Kerunia cornuta specimens reflects shallow agitated and bioturbated environments. •Kerunia cournuta collected from of Upper Eocene of Egypt.•Kerunia is encrusted with Hydractinia and affected by bioerosion.•Hermit crab is recorded in Keunia for the first time in Egypt.