How do lava tubes form? View Available Hint(s)for Part A Hint 1for Part A. The Material That Forms the Tubes Think about which type of flow forms the lava tubes inside volcanic conduits. Pahoehoe flows change into aa flows, which develop cave-like tunnels that were previously used for carrying lava from an active vent to the flow's leading edge. Aa flows change into pahoehoe flows, which develop cave-like tunnels that were previously used for carrying lava from an active vent to the flow's leading edge. Pahoehoe flows develop cave-like tunnels that were previously used for carrying lava from an active vent to the flow's leading edge. A mix of aa flows and pahoehoe flows develop cave-like tunnels that were previously used for carrying lava from an active vent to the flow's leading edge. Aa flows develop cave-like tunnels that were previously used for carrying lava from an active vent to the flow's leading edge