Some tafoni (pattern of little weathering pits) expressed on Malmesbury Group (~700 Ma) turbidite sandstones at a little outcrop on the eastern shore of False Bay, South Africa:
That last one seems to have some concentric layering to the tafoni pits – exfoliation? Spheroidal weathering? Hmm…
Reminiscent of the box work at Wind Cave NP in South Dakota…http://www.nps.gov/wica/naturescience/speleothems-boxwork.htm