The Louisiana pearlshell mussel is oblong and kidney shaped. Umbos (the inflated dorsal part of the shell) are even with or slightly extended past the hinge line. The anterior end, typically buried in the substrate, is rounded; whereas, the exposed posterior end of the shell is pointed and may have some corrugated sculpturing along the surface of the shell. Large adults are approximately 100 mm (3.9 in) long, 50 mm (2.0 in) high, and 30 mm (1.2 in) wide.

The periostracum or outer shell color is brown to black, while the nacre or inner shell color is white to purple, with the nacre surface being pitted.

The periostracum or outer shell color is brown to black, while the nacre or inner shell color is white to purple, with the nacre surface being pitted.

The reproductive biology of the Louisiana pearlshell is similar to other dioecious (having separate male and female sexes), freshwater mussel species, in that fertilization occurs after females siphon and filter sperm that males release into the water during the spawning period. The sexes are monomorphic (males and females appear the same). Females brood developing embryos on portions of all four gills until releasing fully developed larvae, called glochidia, into the water. These glochidia must then attach to a species-specific host fish within a short time after being released into the water or the released glochidia will die. Once glochidia successfully attach to the gills of the host fish, glochidial metamorphosis takes place over about a month. After glochidial metamorphosis is complete, the newly metamorphosed mussels are released from the host fish and float downward to settle on the streambed. Once reaching the sediment in suitable habitat, the final developmental stage into a sexually mature adult begins. It is not yet certain at what age the Louisiana pearlshell reaches sexual maturity, but recent published literature indicates five years. Juvenile mussels are capable of pedal movement to attempt to find suitable habitat if the location drop-off occurs is unsuitable. Several fish species have been suggested as potential host for the Louisiana pearlshell, but until 2016 all reports of potential host fish were made from observing glochidia encysted on the gills of wild caught fish, with none confirmed from observation of metamorphosis into transformers. The U.S. Fish and Wildlife Service's Natchitoches National Fish Hatchery estimated reproductive timing of the species in the wild by observing females. The grass pickerel is documented as suitable host fish to produce juveniles in captivity.

Streams with Louisiana pearlshell are spring-fed, relatively narrow (less than 4.9 meters in width), clear, moderately swift-flowing, headwater streams having stable mineral substrate, such as a sandy bottom with rocky outcroppings, and an approximate riffle-to-pool ratio of 3:1. Within these streams, Louisiana pearlshells usually occur in shallow water (12 to 24 inches deep) often in headwater riffles where the stream bottom is dominated by loose, fine or very fine sand with infrequent patches of larger gravel. They are rarely found in deep pools with slower flowing water and silty bottoms, likely due to the species’ intolerance to high silt loads. 

The diet of the Louisiana pearlshell is likely similar to that of other freshwater bivalves, including food items such as detritus (disintegrated organic debris), algae, diatoms, and bacteria. Adult freshwater mussels are filter feeders and generally orient themselves on or near the substrate surface to take in food and oxygen from the water column. Juveniles lack developed filter feeding structures and typically feed using their large muscular foot (pedal feeding); they burrow completely beneath the substrate surface, bringing food particles that adhere to the extended foot inside the shell for ingestion.