The birdwing pearlymussel (Lemiox rimosus) is a rare species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of freshwater mussel in the family Unionidae

Unionidae

Unionidae is a family of freshwater mussels, the largest in the order Unionoida, the bivalve mollusks sometimes known as river mussels, naiads, or simply as unionids.The range of distribution for this family is world-wide...

, the river mussels. This aquatic

Aquatic animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 bivalve is native to Tennessee

Tennessee

Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...

 and Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

 in the United States. Its range has declined over 90%. It is a federally listed endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 of the United States.

This mussel remains in three rivers in Tennessee and Virginia, the Duck

Duck River (Tennessee)

The Duck River, long, is the longest river located entirely within the U.S. state of Tennessee. Free flowing for most of its length, the Duck River is home to over 50 species of freshwater mussels and 151 species of fish, making it one of the most biologically diverse rivers in North America.The...

, Clinch

Clinch River

The Clinch River rises in Southwest Virginia near Tazewell, Virginia and flows southwest through the Great Appalachian Valley, gathering various tributaries including the Powell River before joining the Tennessee River in East Tennessee.-Course:...

, and Powell Rivers, having been extirpated

Local extinction

Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...

 from many more. It is now extinct in the state of Alabama

Alabama

Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

.
The Tennessee Valley Authority spent nearly $83 million between 1969 and 1983 on the Columbia Dam in Columbia, TN, but had to cancel the project due to two endangered muscle species being found in the Duck River, the birdwing pearly mussel and the Cumberland monkeyface pearly mussel.