Giant tuns are large sea mollusks found in the Atlantic Ocean.
This particular giant tun was in a shell larger than your fist. It was found on the beach between the ferry drop off point and the dock on the western end of Shackleford Banks.
According to Cape Lookout National Seashore, finding a giant tun shell would've been a rare find, but finding one with the animal still alive inside is absolutely incredible.
The animal was released back into the water after having its picture taken a few times.