Not just thrown around though—you can get crafted looking things through natural geothermal processes (which probably are no longer happening on Phobos); column

Not just thrown around though—you can get crafted looking things through natural geothermal processes (which probably are no longer happening on Phobos); columnar basalt is one of my favorite examples https://en.wikipedia.org/wiki/Basalt#Columnar_basalt https://en.wikipedia.org/wiki/Basalt#Columnar_basalt (If you live in California, Devils Postpile is worth a side trip from Yosemite).