This image is of an Anadara sp. pelecypod fossil. The fossil appears to be made of plaster/gypsum/calcium sulfate and in a translucent form. The creature existed in the Miocene Epoch of the Neogene Period. Fossil was discovered in the Sahara Desert at Ajdabiya, Libya.
Picture taken at Museo di Geologia e Paleontologia Florence Italy (Università degli Studi di Firenze) on August 2019. Specimen donated by Dr. P. Vannocci.