"Boulder carved over its upper surfaces, but the sculpture is now broken and eroded. Like Monument 14, when first encourtered by Maudslay, this sculpture was in the grip of a large tree. The much better preserved southern face has a central grotesque mask with fleshless jaws. Monument 15, like Monument 2, seems to depict the cosmological reptilian monster.
...Hieroglyphic panels are carved above and below the mask on the southern side. The lower band, divided by the mask's lower jaw, begins at the left (west) with an Initial Series date 18.104.22.168.0 rendered in bar-and-dot notation."
Robert J. Sharer, Quirigua: A Classic Maya Center & Its Sculptures, Carolina Academic Press, 1990, p. 57-58