The Cenomanian-Turonian rocks of Gebel Areif El-Naqa and Wadi Quseib (eastern Sinai) yield associations of echinoids and other macrobenthic faunal elements (e.g. oysters, gastropods, corals). Twenty-six echinoid species (thirteen regular and thirteen irregular) belonging to sixteen genera, fourteen families, and eight orders are identified, systematically described, and their stratigraphic and palaeogeographic distribution is discussed. Based on a functional morphological analysis, the mode of life and feeding of the different taxa is reconstructed. Two main types of facies have been recognized in the studied sections: marl and reefal carbonates. The marly facies is dominated by burrowing and ploughing irregular echinoids, whereas the reefal carbonates are dominated by grazing epifaunal regular echinoids.
Some of the echinoid tests (e.g. Heterodiadema libycum) together with oyster shells have been affected by bioerosion and encrustation.