An organized group of individuals, amateur and professional, interested in the phylum Mollusca. Although the name implies only shells (of marine, freshwater, terrestrial, arboreal, marine and fresh water molluscs), club members often have broader interests to include those molluscs without shells as adults (e.g., nudibranchs, ascoglossans, cephalopods, aplacophorans). Typically, regular meetings are held, presentations are made, and field trips organized; often, a newsletter and/or website is published. A list of shell clubs (and related organizations) is maintained on the Conchologists of America (COA) website. See also: MALACOLOGICAL SOCIETY.