For this Fossil Friday, we have the right valve of a jewel box clam called Chama berjadinensis. This specimen is from the Gatún Formation of Panama and is Late Miocene in age. Clams are bivalve molluscs (Class Bivalvia, Phylum Mollusca) and are so named for the two valves that make up their shell. The outside of the valves of Chama berjadinensis can have irregular or even frilly growth lines radiating out from the umbo (usually the highest point on the valve, near the hinge line) that run parallel to the shell margin.
To find out more about this specimen, read the Fossils of Panama page on Chama berjadinensis from the Gatún Formation here.