Annona muricata (Cherimoya relative)

I was watering the tropical room a few days ago and noticed a strange flower growing out of the trunk of one of the small trees.  It was located about 50cm above the pot.  It looks like a highly textured origami flower!  I've never seen anything like it before (at least in real life).

I asked the greenhouse manager what it was and she said it was related to Cherimoya.  I did some researching online and it seems to be Annona muricata.  I'm not entirely sure this is the correct species so if I'm wrong just let me know.  It has several male and female flowers and I'm hoping at least one of them develops into fruit.  I'll make sure to post a picture if it does.

UPDATE:  The outer case just dropped off and left a little 'cylinder' that had about equal height and width.  This had several dozen tiny stamens around the perimeter.  It looks kind of like one of those spin brush heads but with only the outer bristles.  I forgot to get a picture but if it's still there next time I'll try and take one!