flowstones like this are formed by water saturated with calcite minerals flowing down the walls and over other exposed rock surfaces and being deposited over them in very thin layers which slowly build to a thickness of several feet in very old cave systems.
these also form into strange and fascinating formations by a combination of gravity and air flow currents within the cave.

taken with cannon 350d digital SLR, 18mm lens [1 sec. f6.3]
backlit with remote operated flash gun