"An irregular flat boulder, some 3.8 m (11 1/2 feet) long and .5 m (1 1/2 feet) thick. It is carved over its upper surface, overlapping somewhat onto its sides. The northern third of this exquisite sculpture depicts a spectacular figure, representing either a human dressed in the costume of a god, or a deity, poised against the coils of a gigantic, spotted serpent rendered in bold and deeply carved relief. The figure's feet point to the west, the right leg drawn upward as if dancing. His head, turned to face northwards, is adorned with an elaborate headdress and his face is covered by a jaguar mask. The right hand grasps an apparent masked-shield, held in profile, while the left arm is thrown above the head holding another mask. The entire composition is a skillful and vivid depiction of a figure in motion, rare in Maya art, and was considered by Sylvanus G. Morley to be the finest example of its kind in the Maya area.
The southern two-thirds of Monument 23's upper surface is carved in an elegant hieroglyphic inscription. This begins with a central T-shaped panel of large and complex full-figure glyphs recording the Initial Series date read as 18.104.22.168.8 9 Etznab 1 Kankin, the day of Sky Xul's inauguration as ruler of Quirigua. This leads to an outer panel, following the same T-shaped outline, containing a lengthy historical text. The latter includes mention of Cauac Sky and his successor Sky Xul, with the latter's apparent titles, and the Quirigua "emblem glyph." There are references to several historical dates, such as Cauac Sky's capture of 18 Rabbit, ruler of Copan (22.214.171.124.6), and others of unknown significance. "
Robert J. Sharer, Quirigua: A Classic Maya Center & Its Sculptures, Carolina Academic Press, 1990, p. 58-9