I suppose this one will be difficult to answer. But, here
goes nothing.

In a pivot table when you move an item into the page field
or the data field, etc. you have a clickable item that
gives you options for that item in the pivot table.

If you dig, you find that the page fields and the row field
are comprised of multiple parts. The little buttons that
you click for the selection choices are actually a members
of the sheets' Shapes, with the names "Drop Down 2" &
"Drop Down 4" & etc. You can manipulate these objects
without a problem. What I can't find is the gray object
that is usually titled "Sum of ..." or "Count of ..."
and also contains the title of your page field selection.

Now my assumptions are as follows: The formatting of these
items are not tied to the cell, because they don't copy
with the cell contents, but they can be dragged with the
cell. They act strangely because with a normal shape
object you can set it to not move or size with cells,
and then it cannot be copied. But these "shapes" can be
sized with the cell, but don't move with cells???
Curious, indeed! Also if you copy a pivot table and paste
values over the same area it effectively kills the
pivot table, but the objects remain. However, if you
change any of the properties of the cell you get rid
of the left over object. It's very baffling, it looks
almost like an cells interior setting, but you if you
have two together part of the selection tool will be
covered by the upper or lower object, which normally
couldn't happen with a cell, but only with shapes or forms.

Also, the ability for these items to be pulled from the
sheet suggest that they are a different kind of object.

Figuring this out is interesting, because it really opens
up some different applications. For example it is already
possible to simulate the commandbar that is used to shuffle
items with the pivot table, with this in mind a 'shuffleable'
calendar could be integrated with Excel, where you drag and
drop the days, weeks, or months onto the sheet and either
convert them to values or hold them as objects.

Anyone who can figure this out would I would be very
envious of.