Hi Tre
I know I'm not Paul, but i'll try to "give it a shot"
It sounds like the shell named skymine, niagra-falls-shell, horsetail, or falling-leave-shell. These are not "exploding" but breaking while igniting the chemicals inside, which have a long burning time compared to ordinary shells like peonies.
I don't know it that was what you meant? As far as i understand it's coloured, silver or golden shells you are referring to and not glittering/flashing?
Regards,
Lars