The all-at-onceness of conscious experience

As we encounter things in the world around us, when do we judge something to be just a heap or aggregate of smaller things, like a pile of sand, and when do we judge it to be a true, unified, single thing? It depends, almost always, on how you look at it. I have argued that when we look at the world in strict reductionist terms, nothing above the sub-atomic level really counts as a holistic thing. Are there any things above the micro level that really are inherent, single things in a way that does not depend on how you look at them? Do we have any reason to believe that there are, in contrast to the reductionist view, inherently unitary mid-level things in the universe?