The molluscan seashells of the Moodys Branch Formation lived in a tropical/subtropical sea that advance across the Gulf Coastal Plain of the Southeastern United States in a global sea level rise that occurred in the Late Eocene Period around 38 million years ago. They lived in the nearshore sands and shallow offshore waters of the advancing seaway. The preservation and diversity of these fossil shells are exceptional and are only rivaled by Late Eocene faunas of this age in the Paris Basin of France. Some shells show their ancient color patterns under ultraviolet light.

Fossil mollusks illustrated here are largely from the collections of Mississippi Department of Environmental Quality Office of Geology's facility at 2525 North State Street, Jackson, Mississippi, and are designated with figured specimen numbers. Others are from various museum collections as designated. Many were original illustrated in Office of Geology Bulletin 120. Illustrations here are in higher resolution and in several views. Image files are arranged alphabetically and then systematically under the Classes Bivalvia, Cephalopoda, Gastropoda, and Scaphopoda.