Entering

The blue steaks in this image are places where water has dripped for many years to leave a manganese oxide patina.

I believe they used these streaks like a portal, a place to enter the rock. Note the crack that goes right through the heart, cracks in the rock can be a place to enter or exit the rock.
I don’t think the Shaman physically entered the rock, yet in deeper states of consciousness could “enter the rock.”