In my original posting I mentioned that there were many more. Actually there are so many that it is not unlikely, as you say, that these are a by-product of the RAT. In that case it is a pity that the RAT is polluting the sample to such extent! Can we get somewhere some description of the RAT effects on similarly packed formations (here on earth)?. Some of the grain strings (mini-macaronies) are in crevices...are those sheltered from the RAT action? I originally thought that since there were so many random grains around, it wouldn't be extrange to find, here and there, either strings or clusters of cemented grains...that could also explain the formation of the large macaroni. Being size something relative and given a certain image (of given resolution), and knowing to which extent the RAT disturbs the sample, could we draw a line on features that are, or are not, interesting or significant based on size/per pixel?