Its only one rock; not a bunch of rocks. I took sent these photos to a shamanism site and there reply was.
He had drunk, and now he sang softly. Gradually, faint lines and forms began to appear in the darkness, and the shrill music of the spirit helpers, arose around him. The power of the drink fed them. He called, and they came. First, the anaconda, coiled about his head, transmuted into a crown of gold. Then the giant butterfly, hovered above his shoulder and sang to him with its wings. Snakes, spiders, birds, and bats danced in the air above him. On his arms appeared a thousand eyes as his spirit helpers emerged to search the night for enemies.
The sound of rushing water filled his ears, and listening to its roar, he knew he possessed the power of the first shaman. Now he could see. Now he could find the truth. He stared at the stomach of the sick man. Slowly, it became transparent like a shallow mountain stream, and he saw within it, coiling and uncoiling the poisonous serpent, who had been sent by the enemy shaman. The real cause of the illness had been found. At this time he picked up a two pound rock and sucked the serpent from the sick man and placed it in the rock.