The Nettle Cave
The Nettle Cave lies between the Grand Arch and the Devils Coach House.
The cave takes its name from the nettles which grow near its entrance (note that raised walkways protect visitors from their stings); an upper part of this cave can be seen from inside the Devil's Coach House.
Originally shown as a guided tour, the cave was closed to the public in 1932 and re-opened in 2006, combined with the adjoining Devil's Coach House. The Nettle Cave hosts "Crayfish backs",stromatolites shaped by cyanobacteria, light and wind.
They are estimated to be at least 20,000 years old.
Image and Information Thanks to Wikapedia:
Public Domain, https://en.wikipedia.org/wiki/Jenolan_Caves