The tunnel was uneven, narrowing and widening irregularly as it made its serpentine way into the earth. In the places where he had to duck low, Sam almost felt the weight of the rock above him. The walls were smooth and the tunnels almost circular. Branches too small for a man to pass through split off from the walls and ceiling. Sometimes the flashlight’s beam showed that they looped back in almost immediately. Most often they were simply stygian holes impenetrable to the probing light. The effect gave an uncanny organic feel to the place, as though they were walking through the arteries of some strange being of rock.