It's like a "Christmas in a waterdrop"
Diptera pupa... floating on the bottom of water... a few seconds after, emergent new adult has left the exuvia
As I recognize (if i'm not wrong) a Chironomidae/Chironominae/Tanytarsini as they were a few larvae in the same sample
nevertheless I've lost the exuvia, in the same time of following the new adult moving on a piece of paper... and I couldn't go ahead in the determination
Don't hesitate to shut down my belief if you think I made a mistake