7. While taking Instagram selfies near a volcanic vent in Hawaii (and paying attention so as to not get distracted and step in hot lava), you find an interesting rock (see

picture below). It has a very dark color, no visible crystals, and vesicles that look like air bubbles. What is the name of this rock? Is it igneous, sedimentary, or metamorphic? How did it form? Did it form on the surface or underground?