Flowing lava leaves its mark in many ways. The simplest of these are flow lines, etched into the walls of the cave or floor of the cave.. The lower photo shows a phenomenon sometimes seen in places where two major conduits converge, leaving a v-shaped point aimed in the direction of the flow at the head of the passage wall that divides them. These are called “ship’s prows” for their resemblance to such a feature. The one below has an unusual hanging “mini-prow” suspended above and pointing the same direction as the prow beneath it: downflow.