"I should like all artists to sell their fingerprints, or else stage competitions to see who can draw the longest line or sell their shit in tins. The fingerprint is the only sign of the personality that can be accepted: if collectors want something intimate, really personal to the artist, there's the artist's own shit, that is really his."The actual contents of the cans remains a much disputed enigma, since opening them would destroy the value of the artwork. In 2007 one of Manzoni's collaborators, Agostino Bonalumi, revealed that the tins are actually filled with plaster. However Manzoni's girlfriend Nanda Vigo, who helped to produce the cans, has claimed that they are actually filled with feces and an art dealer from the Gallery Blu in Milan claims to have detected a fecal odor emanating from a can. It is likely that the contents will never be revealed but that doesn't seem to concern collectors. In 2000 The Tate purchased a can for £22,300 and most recently cans have been sold for €124,000 and £97,250 in 2007 and 2008, respectively - quite a large increase from the original $37 in 1961. Actual feces or plaster, "It is a joke, a parody of the art market," Stephen Bury says, "a critique of consumerism and the waste it generates." Manzoni believed that the gullible art world would purchase anything signed by an artist, even a tin of feces.