The device in the box was a portable sonar rig. It was capable of sending out pings, but that wasn’t how they were using it. They were using it to listen. Sonar Taxlaw had virtually wrenched it from Ty’s grasp and mastered it. The arrival of Ark Darwin and the movements of the boats and the barge had caused her no end of annoyance, but with a little encouragement from Ty, she’d begun to see it as an interesting science experiment, a way of understanding what those technologies must sound like to Pingers and other mammals that frequented the deep.