Whats happening here?

Ok so 3 days ago I decided to do a lil experiment. I have heard of people putting frozen shrimp in their tanks to help kickstart the cycle process in a new tank. so I did. (tank isn't new, but I just recently moved and set it up) and instead of taking it out I just left it. after a day or so it grew this transparent type film around it and stayed like that until today. then as im writing my last post I watch it go from laying on the sand bed to rising just like a hot air balloon to the top. Is this a good sign? I did it because at the end of the nitrogen cycle nitrates get turned into nitrogen gas and that's how nitrates leave the system correct? (well along with water changes & whatnot) was I correct in my thinking? during this whole process I never has a spike in ammonia or nitrites, my nitrates however are off the chart because of a rock I pulverized and put back in when I sold the eel that came with the tank



don't worry I really have nothing in my tank to kill so I can do silly stuff like this, basically all I get to look at is the cool design I made with my live rock, a hitchhiking pest anemone and 2 snails