Cuélebre

Cuélebre (Asturian) or Culebre (Cantabrian), is a giant winged serpent-dragon of the Asturian and Cantabrian mythology, that lives in a cave, guards treasures and keeps xanas / anjanas as prisoners. Although they are immortal, they grow old as the time goes by and their scales become thick and impenetrable, and bat wings grow in their bodies. They don't usually move, and when they do it, it is in order to eat cattle and people. One can kill the cuélebre giving him as meal a red-hot stone or a bread full of pins. Its spit it is said to turn into a magic stone which heals many diseases.

In Midsummer, which is a magical night in Asturian and Cantabrian folklore, it is possible for brave men to defeat the cuélebre, whose spells don't take effect that night, and marry the xana and get the treasure. However in Cantabrian areas it's said the night of Saint Bartholomew the creature increases his power and unleashes all his fury against people in revenge.

When the cuélebre grows older its scale become thicker and thicker, and he must flee Asturias and fly to the Mar Cuajada, a paradise located beyond the sea.