It all started in this Feud from back in 2008. One of the questions was “Name a variety of seashell”; and the most popular answer by far was “Conch.”
Which prompted brujaja to say:
In the Feuds that followed, whenever there was a question where one answer turned out to be the overwhelming favorite, it got referred to as “the conch.” (For example, twickster’s comment: “Oh well, every game needs a ‘conch.’”)
Eventually, Rebo gave us “The Conchless Feud” (Directions explained “The following ten questions produced conchs in earlier feuds. Here they are again, with the conch banned as an answer”).