Rudist block

This partially silicified block is of unknown provenance, most probably collected during an expedition to northeastern Sinai in the 1970’s and rescued from the storeroom of the geology department. It is characterized by large elevator-type rudist bivalves that are individually solitary, but fan out to form interlocked bushes of adjacent upright conical shells stabilized by interlocking of prominent ribs. Such mutual support enables them to grow upwards to heights of more than a meter above the sea floor, and they are considered to have formed reef-like barriers on the paleo-continental shelf. They are accompanied by several other species of molluscs, most notably large nerineid gastropods.​

The outer shells of these rudists were thick, light and strong, composed of mesh- or honeycomb- like walls originally of magnesian calcite with a high preservation potential, whereas inner shell layer and tooth- and muscle scars were original aragonite, which tends to be more readily dissolved. In this material, an early stage of silicification allowed preservation of much original wall structure.

Also present are large nerineid gastropods with an internal screw-like columella, similarly of aragonitic mineralogy and stabilized by silicification. Original dissolved-out walls had been attacked by clionid sponges, which were infilled prior to solution and are well preserved.
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The material appears to have affinity with the outcrop from the Turonian described by Parnes (1987) from the Praeradiolites lewyi lewyi beds at Gebel er-Risha in eastern Sinai. It is also similar to a section of the Turonian Wata Fm. described by Saber et al. 2009 at Gebel Minshera, from which Nerinea requienianum was recovered at the same level. ​​