👉 The term "spleenolith" refers to a type of mineral in humans that is composed mainly of calcium carbonate. Spleenoliths are found in the digestive system and can be either solid or fluid, depending on whether they are solidified by minerals like iron or magnesium. Spleenoliths were first discovered during the 1800s by scientists working at the University of Paris under the direction of Jean Baptiste Leclerc. They were named for the spleen