For years I have seen these for sale as megalodon coprolite. If megalodons were anything like modern great whites, their feces would be watery and not at all solid. Diving in Florida's rivers for fossils, I come across fresh alligator feces and it is just like this. I'm no expert, but since crocodile fossils are found in South Carolina rivers, where this was found, I would feel rather comfortable calling it crocodile coprolite. Furthermore, I have yet to see any coprolite from some of the top megalodon producing sites in the world. Chile? New Caledonia? Peru? Venice,FL?
Some look more like poop that others. This one is unmistakable.
These are popular as gag gifts.