Brought to you from the Natural Bridge Caverns, near San Antonio, Texas — it’s the King’s Throne:
Honestly, I’m not sure where they got the “throne” part of this — looks more like a geological Cthulhu to me. Just the same, it’s an impressive formation.
The Natural Bridge Caverns are in the heart of Texas’ “hill country,” essentially an old limestone plateau since shaped into hilly scrublands by underground erosion and subsequent collapse (much like what happened in the northern Yucatán peninsula). These caverns were formed when the water table lowered, and an eroded underground space gradually was decorated by stalactites and stalagmites formed when water percolated through the surviving limestone overhead, carrying minerals (largely calcite) into their new home.