Dragons were believed to live at the bottom of the sea (Water) or in deep caves of high mountains (Earth), where they guarded vast treasure hoards, very frequently of pearls and stones. Usually dwarves are looking after them in popular fairy tales.
Ladon, the dragon of Greek mythology guarded the Hesperides gardens and the golden apples until Herakles defeated it.
In Norse mythology, Fafnir was the guardian of Rhine gold.
Powers of dragons