In Late Roman and Medieval Folklore, the Pirobolus (plural Piroboli) were gendered rocks (male and female) which if they were brought close together, they would burst into flames. They were reported to only be found in the East. They appear in Physiologus (200s- 300s CE) by Unknown. Other names for them: Lapides Igniferi, Lapides Piroboli, Cheroboli, Terrebolen, Terroboli, Turrobolen, Deus Perres, Douze Pierres. All of these names mean "fire stone" (it is possible the best spelling of this would be Pyrobolus). Puroboros is apparently a misspelling of the name originating from Final Fantasy V & Final Fantasy X, which had Bomb monsters with this name.