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This next species is the second most common animal found in the Essex portion of the Mazon Creek deposit. While there are over a dozen described bivalves found in the Mazon Creek deposit, Mazonomya is by far the most abundant. It is restricted to the Essex (marine) portion of the deposit, where in some areas have been found to make as much as 70 percent of all bivalves collected. At one collecting site, these clams are so common the area has been nicknamed Chowder Flats. Despite the abundance of specimens, Mazonomya was not formally described until 2011. For years it had been misidentified as a type of bivalve named Edmondia. Current research has shown it is actually a Solemyid. Before formal description, Mazon collectors referred to these bivalves as clam-clams due to the fact that they are often preserved in a death position with both valves opened. Mazonomya is the largest clam found in the deposit . While quite rare, specimens have been found over 4 centimeters in length. preservation can be excellent and in some cases, soft tissue can be preserved. Specimens have been found with preserved “death trails”. Solemyids are still found today in oxygen poor and sulfide rich marshes. This first specimen is the largest in my collection. The valves measure almost 4 centimeters. There is also some evidence of the hinge ligament (soft tissue) between the valves.