Writing to Norman Muller:
I believe the "pyramids" are burial mounds. The "hollows" are because the body was surrounded with branches and organic materials which, decomposed, have fallen in. I have examined the inner surface of several hollows that were well faced with squared-off stones, indicating the hollow is deliberate and (to me) clearly part of the initial mound design. It is neither a "thunder bird nest" nor a disturbance from vandalism. It is simply a collapsed inner chamber. The occasional "tail" was an open topped part of the mound. I speculate that this had a mortuary function auxilliary to storing the final remain. Perhaps it was for de-fleshing.
Many of the mounds have two hollows, indicating a paired burial. Some have one, some have a very large hollow suggesting a group burial. I have seen several sites where there is a mixute of several one-hollow piles together with one "group" burial. That sort of thing suggests a hierarchical tribal structure.
I do not believe the satellite mounds are for "veneration" but, rather fall into the category of what I call "marker piles". They usually have one vertical face and are usually arranged carefully, not at random, about the larger mound. Interestingly, often the mound is easy to miss, and people only notice the satellite piles. I also believe that late in the history of these things, the burial mound was abandoned but the marker piles continue. I think they are for astronomy and believe they are fundamental to the soul's transfer into the heavens.