I had to google “design transit system with slime mold”. Definitely piqued my interest. I think unique ECs will definitely make you stand out, but you need to make sure they come off as meaningful activities and not weirdness for its own sake.
Your applications are in and decisions will be out soon. There is no value to wondering how admissions officers will view your ECs – nobody here was sitting in on those conversations and any comment would just be a guess. At this point I suggest you take a deep breath and try to relax.
I had a kid who apparently was able to sell a weird EC (making and selling origami earrings) to much better acceptances than either he or I would have expected. I know the waiting is hard, but I feel sure you will have some good choices soon!
You need to be unique, interesting and personal to the colleges. Yes, these will make you stand out and pique some interest but don’t be to cute with it either. If you can write and talk about it with passion and interest then you are on the right track. Try to meld it with your college interests and your golden.