Amphisbaena

In some classical accounts the amphisbaena is given a mythic origin: Lucan (Pharsalia) relates that amphisbaenae were spawned from the blood that dripped from the Gorgon Medusa's severed head as Perseus flew over the Libyan desert, placing the creature genealogically among monsters produced by Medusa's blood. This Lucanian origin is one attested classical tradition alongside other natural‑history listings that treat the creature as an exotic animal of Libya or India (as in Pliny and later travel lore).

Core descriptions across classical and medieval sources depict a serpentine or lizard‑like creature with a functional head at each end of its body—one in the normal anterior position and a second where a tail would normally be. Because of this arrangement it is said to be able to move forward or backward without turning. Medieval and later illustrations and bestiary variants sometimes add features such as feet, wings, horns, or dragonlike embellishment; some later descriptions depict glowing eyes while Nicander (an early source) describes it as "always dull of eye," and his phrasing suggests blunt chins at both ends.

Classical sources emphasize bidirectional locomotion (it can run or retreat using either head as the lead). Accounts of diet vary: Lucan places it scavenging on corpses in Libya, while some lexica or summaries call it an ant‑eating serpent (the dietary claims are inconsistent across sources). Later folkloric claims and materia medica attribute a range of human‑directed uses to the animal or its parts—Pliny reports folk practices such as wearing a live specimen for safe pregnancy, wearing the skin as a supposed cure for ailments like arthritis or cold, and nailing a carcass or skin to a tree to keep woodcutters warm—but these are recorded as beliefs or remedies rather than proven inherent supernatural powers.