The Siguerans often used round devices, approximately three inches in diameter and an inch thick, that stored information and opened doors, or revealed secret entrances. These "key-maps" are very valuable in that they lead an artifact hunter to great rewards. The crystal in the center has varying colors based on the type of information stored in it. It is not certain whether this is related to the information, or if it was merely an aesthetic choice.
The most valuable key-map is the elusive "Constellation Crest," a master key-map with information on many of the Siguerans' greatest secrets, and could lead Lancaster to the Siguerans themselves.