One of the most common shells that is found within the Navesink formation in New Jersey is Pycnodonte. There are a couple of species with the one I'm showing you today being a Pyncnodonte convexa. It was found at Big Brook near Marlboro, New Jersey in the Navesink formation which is upper Cretaceous (Maastrichtian stage) in age.
Left valve top
Left valve anterior
Left valve, right side profile
Left valve interior
Left valve, left side profile. Note the worm tube that is embedded in the shell.
Left valve posterior
Here are a couple of the right valves which are smaller than the left valve and slightly convex.
Right valve top
Right valve interior
Right valve posterior
Right valve profile
Shells of these oysters are often colonized by epibonts such as sessile worms, sponges and bryozoans. You can see some Bryozoans that have colonized the gaps in the right valve shell below.
Here is a closer view of the worm tube that I indicated above: