pahoehoe
basaltic lava that has a smooth, billowy, undulating, or ropy surface, due to the movement of very fluid lava under a congealing surface crust
en-US/pəˈhoʊiˌhoʊi/
basaltic lava that has a smooth, billowy, undulating, or ropy surface, due to the movement of very fluid lava under a congealing surface crust