Leontophone is a small animal from Medieval bestiaries that is deadly to lions. To kill a lion, the lion need only bite it. But, more properly, in a ritual, the flesh of a leontophone is burned and its ashes are sprinkled on meat, which is placed at a crossroad; if a lion eats even a small amount it dies. Lions hate leontophones and hunt/kill them, tearing them apart with their claws rather than biting them.[1]
No sources are referenced as to the leontophone's appearance.