Each year a miracle occurs in a small Greek village in Kefallonia. Between the feasts of Transfiguration (August 6) and the Dormition of the Theotokos (August 15), snakes with small crosses on their heads and tongues come from the bell tower and enter the church to venerate icons. They disappear after Dormition until the next year.
You can read about the history of the snakes in the article The Holy Snakes of the Virgin Mary in Kefallonia (Part 1). Pictures of the snakes are in Part 2.
You can also see videos of the snakes below.