Hubby took this shot of one of the 'sisters'.
I have no idea what these protrusions are. They seemed to have a 'shell' of some sort but that's all I can tell you.
This shot from inside one of the caves made Hubby's shot look quite tropical.
There are lots of caves along the river in lots of different sizes.
I just love the patterns made in the black sand by water ripples.
These rock layers just amaze me.