pixie dust transition

OK, I am old. The mind is lapsing.

I made a FCPX video in which a transition has kinda-like pixie dust being scattered over the picture. My brother wants the unlying picture to be slightly different... so I need to remake the video. But I don't have the original FCPX work. No problem remaking it except that I cannot remember what the name of the generator or transition is.

Does someone know it?

Many thanks,

Diane