This upper Cretaceous oyster is characterized by long and curved valves. Stout ribs cross the upper valve. The sample is obtained from Ariyalur/Dalmiapuram area. samples collected by Riffin T Sajeev and Russel T Sajeev from World Fossil society.

The Rastellum genus of oysters lived between 161 to 65 million years ago during the Jurassic and Cretaceous periods. Occurring in many locations across the globe, the Rastellum oyster species inhabited shallow marine environments such as lagoons, bioherms and biostromes, and peritidal areas exposed to air and more harsh extreme variations of temperature, salinity, and storm activity, and also lived in shallow subtidal areas, above, on, and below reefs, coastal areas, and offshore shelves along continents. Rastellum oysters would remain stationary, attached to the surfaces of rocks, pilings, and to the sea floor itself, where they would filter feed on small foods suspended in the water column. This specimen is Rastellum carinatum, a species which seems to have occurred from 144 to 65 million years ago, evidently becoming extinct during the same event that ended the reign of the dinosaurs.

Rastellum Carrinata from Ariyalur/Dalmiapuram : Photo copyright@ WFS,Riffin T Sajeev&Russel T Sajeev