Crysmals are the magpies of the Plane of Earth—that is, if magpies hatched what they stole and were shaped like scorpions to boot.
A crysmal has crept its way out of a sinkhole in a poor country parish. Lost and ill from the wet climate, the crysmal has hidden from prying eyes, stealing only cheap quartz crystals from the mosaic in the local chapel. When a jewel-bedecked sheriff rides into town, however, the crysmal strikes. Knowing only that he has been robbed the sheriff’s investigation of the parish turns brutal.
An earth elementalist leads an exhibition to the Plane of Earth to study crysmals. What he does not reveal is that he is also a budding artificer. He studies crysmals in the hopes they may unlock the key to his true aim: the creation of self-replicating golems.
A djinni vizier’s jewels are missing; crysmals are the cause. The djinni blames a recent guest, a shaitan he recently hosted out of duty, not desire. But if the trail is followed, the shaitan is revealed to be innocent. In fact, he is also victim—his mardana has been overrun by the creatures, which have consumed his treasure horde and bred like rabbits.
—Pathfinder Bestiary 2 61