Yeah, I thought Sel forgot about it or maybe it was supposed to be used together with other science fair mentioned content in event we never got. But maybe this Chekhov's gun is still loaded.
Probably wouldn't be too useful for Ami's parents considering their physical forms should be spooky scary shattered skeletons.
But Sana's participation makes me think it's connected to her brother who's supposedly still active in spirit from.
Or maybe Sensei will get decapitated by a Kendo champion for violating Molly and conveniently resurrected by this.
Can't think of anything else with ressurect potential, and we can only wonder about the method.
Pseudo Dark Theory Time: I'm not entirely convinced most of the class is actually alive, and this science fair stuff could be a subtle plan by those in the background, intended to bring the girls back to life.
Yasu seems to claim certain girls only exist when needed:
And with Nodoka's recent "love story":
It seems like Sensei might be perceiving these girls as alive when they are more like corpses, that he pretends are alive. Possibly like shells of themselves. Hence stuff like Egg time.
In other words:
And Yasu was asking this for a reason:
This ressurection thing could be a scheme that is being whispered to Ayane through the voices in her head (which she may or may not actually hear, considering the complications with this scene):
Or it has nothing to do with the girls, and The World Itself has been merely trying to resurrect and restore itself in various ways.
Of course, I could definitely be way off the mark, and it's just a random subplot that doesn't mean anything.