Part of Hall of Planet Earth.
AMNH/R.Mickens
These pillars were collected on the East Pacific Rise. The cold water solidified the surface, which insulated the molten lava inside. Seawater trapped under the molten flow percolated upward, cooling the surrounding lava and creating pillars of solid rock within the flow. When the flow level decreased, the pillars remained.
Provided by Prof. Dan Fornari, Woods Hole Oceanographic Institution