If someone has a vessel that is muter to move around on Shabbos and it had on top of it something that is "muktzeh" during Bein Hashmoshes than the vessel would be considered a "busis" (a vessel that supports something else) to the thing that is muktzeh and would also become prohibited to move on Shabbos.
Although this might sound funny, if someone had a vessel that was covered in ants or other bugs (which are muktzeh) Erev Shabbos and the person knew about this and didn't do anything about it, would the vessel become muktzeh because of the din of "busis"?
It could be however even though the person knew the bugs were there and didn't do anything about it, still the bugs are not "important" to him at all and could be considered nullified to the vessel itself. However (and this is another point) if there is such an idea when it comes to the dinim of muktzeh and busis, what is the makor for it (that it all depends on how "important" the muktzeh thing is and perhaps it would be considered nullified to the vessel below.)
