astronomy-to-zoology:

Arkansas fatmucket (Lampsilis powellii)

…a rare species of freshwater Unionid bivalve which is endemic to the state of Arkansas in the United States, where it is known to occur in the Ouachita, Saline, and Caddo River systems. Arkansas fatmuckets typically occur in deep pools with enough water flow to remove debris. They are typically absent from areas with riffles or pools that lack waterflow. They prefer sandy substrates and are often seen next to river islands with strands of water willow (Justicia americana) present. 

Currently Lampsilis powellii is listed as Endangered as it is sensitive to environmental changes and only possesses a limited range. 

Classification

Animalia-Mollusca-Bivalvia-Unionida-Unionidae-Lampsilis-L. powellii

Image: FWS

I love you Fatmucket.