Pop art emerged in the late 1950s and utilized imagery from mass media and consumer culture. Andy Warhol was a prominent pop artist known for works like Turquoise Marilyn and Navy Blue John. Arte povera developed in the late 1960s in response to pop art, using common materials like earth, rocks, and paper. Jannis Kounellis' works incorporated natural elements. Dadaism in the early 20th century ridiculed meaninglessness in modern society through works by Marcel Duchamp like The Fountain. Conceptual art from the 1960s focused on conveying ideas over traditional objects, as seen in Joseph Kosuth's One and Three Chairs.