Detail, Nunnery west building. Rising from the lower cornice, a serpent opens its maw to emit either a human or some deity, in a scene evocative of the conjuring rituals depicted on many of the lintels from the site of Yaxchilan. Somewhat above this scene, the rattle of a rattlesnake marks the place where a second snake begins winding through much of this ornate frieze, to end in a similar disgorging scene at the opposite (south) end of this building.