Arcidens confragosus is a species of freshwater mussels in the family Unionidae, the river mussels. It is commonly known as the rock pocketbook, but also has many other common names: bastard, black pocketbook, grandmaw, queen, and rockshell.
This species is widespread in central parts of the United States: it occurs in the Mississippi River drainage and in coastal rivers draining to the Gulf of Mexico, from the Colorado River in Texas east to the Mobile River System in Alabama.
The shell is "" or pear-shaped, heavily sculptured, but fairly thin, up to 15cm (06inches) long. The shell is green to dark brown. The nacre is white, iridescent.