Charles Darwin was the 119th issue in the prestigious Society of Medalists series. Moss was the first non-American sculptor to be admitted into the ranks of Society of Medalists medalists.
According to Moss, the creation of this medal began in 1982 and was inspired by the anniversary of Charles Darwin's voyage aboard HMS Beagle. Moss first crafted the Darwin portrait in clay with "an earthy fossil-like character, and then when I made a cast in plaster the relief took on a bony quality." She was fascinated by the Giant Tortoise and its relation to Darwin. Moss wanted her medal to portray the strength in both man and beast. The result was a bold contrast between a crude and unfinished-looking portrait and a polished tortoise on finished field.
The medal measures 55mm x 73mm and was produced by the Medallic Art Company of Danbury, Connecticut. The edition was limited to 2,500 pieces but the actual mintage is unknown.