Gypsum crystals often develop when it’s too dry for stalactites and stalagmites and water is being drawn out of rock and clay through evaporation (i.e. not dripping through).
Here gypsum crystals curl out of clay. These small mineral structures are formed from the same minerals that created the giant 12m crystals in the famous Cave of the Crystals found near Mexico’s Naica Mine.
In other parts of the Nullarbor, these crystals grow into bigger structures, but nowhere near as big as the Mexican monsters.