"Structure 10L-20, now completely destroyed by the ravages of the Copán River, once displayed an ominously decorated façade. Members of the Peabody museum and Carnegie Institution expeditions record that a series of large sculptures of Killer Bats adorned the exterior of the building. The bats were identified by death signs (%) on their pectorals, and the 'death eye' collars, as the same grisly Underworld denizens described in the Popol Vuh. More recently, we have collected all the surviving fragments of these bats from the Acropolis and the local museum and storage facilities, and calculated that there were at least six of these Killer Bats."
William L. Fash, Scribes, Warriors and Kings: The City of Copán and the Ancient Maya, p. 129