title: Arcidens confragosus
text: # Arcidens confragosus
  
  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.
  
  ## Distribution
  
  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.
  
  ## Description
  
  The shell is "pyriform" or pear-shaped, heavily sculptured, but fairly thin, up to 15 centimetres (5.9 in) long. The shell is green to dark brown. The nacre is white, iridescent.
  
  