That is a common snapping turtle. They never stop growing, I have cleaned one that was over 80 LBS. There are supposed to be 7 kinds of meat in a snapper. I do not know about that but they make good soup and stews.
There is a alligator snapper that has a rougher shell and looks much more dangerous. It is the one I think of when I imagine how a snapping turtles looks, they are less common though.
They can impact fish population in ponds, and usually require control.
They also can remove a finger.
Rod