The title says it all, really.
In social science, the fundamental object is the person to the state, depending on scale.
In life science, the fundamental object is the cell to the person, again depending on scale.
In physcial science, the fundamental object is the elementary particle to the molecule, once more depending on scale.
So, here's what I need naming: the fundamental object in formal science. This object may not exist in physical reality, but it's still worthwhile to name. Any ideas?