Photos: The surface of the moon, here on Earth

According to the National Park service, pahoehoe, "a relatively smooth lava, takes its name from the Hawaiian word for 'ropy.' Pahoehoe lava flows are highly fluid, flowing easily. As the surface of the flow cools and forms a crust, the hot lava flowing underneath pulls the top layer into ropes or coils. The crust eventually becomes a rigid roof, forming a lava tube."

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Photo by Daniel Terdiman/CNET