The ancestors of the aborigines come in all shapes and sizes, in some ways they are very similar to Greek Gods and Goddess', in that they usually represent a certain theme. Such as the sky, or water. During the Dreaming the ancestors crisscrossed Australia shaping the land into its current state as the went. The Aborigines also consider certain constellations to be ancestors.
The great serpents are representative of Australia winding rivers, and water in general. The most powerful and well known serpent is the Rainbow Serpent. The Rainbow Serpent is known in all Aboriginal cultures and is feared and revered by all.