Good evening Forum

I have removed this bar end to put on a bar end mirror and I'd like to know what fell off inside the bar. [ imgur.com/a/P0oYY
Is it just a nut??
I presume the nut fits into that collar which gradually expands [the nut in the pic is just on there to keep it together] the tighter the screw becomes.
Have I got the orientation of the collar right,as I'm sure that is how it came out in the pic?
I would like to know as I cant get whatever was on the end out,and I dont really want to have to take the bar off but might have no choice.
The mistake I made was to do it with the bike in the lock position tilted over to the left I know,but was under the impression that it screwed into an insert that would be locked in position with a clip....
I cant see anything inside the bar and it did indeed sound like a small nut falling off,nothing more.
Hope someone can advise !
Cheers