Mariano Zuzunaga's "Piedras" is a work of conceptual humor. Three stones are aligned in single file, but one of them "breaks ranks" and vanishes leaving but a ghostly trace of itself. If we humanize the image we have a metaphor of dissidence or inconformity. Perhaps it is a refusal of a dissident stone to obey the laws of perspective that force it to get smaller the farther away it is from the viewer. Another reading of the image is more germane to the nature of stone itself and the medium of photography. Zuzunaga uses the intrinsic tools of photography to debunk the relationship between the referents and their images, and between the truth of what we see with our eyes and what we see in a photograph. Rocks do indeed vanish in huge geological times and by using a long exposure to blur the image of one of the stones, the relative short times of photography bring out that important insight.