OK, near rear left wheel under the car, you see a black box that I think is related to the emmision. This black box is connected with some hoses to a while colored rounded thing. Anyway, when I take out the black box, I can hear rattling sound. Then when I tap to the floor, I can see small black particles comming out from the hole. It seems like small black carbon rocks. Is this normal?
What is the purpose of these small black particles? It looks like charcoil.

 

Is it on the drivers side rear wheel area? If so that is your evap box. Yes all that stuff you mentioned is normal. At least so i've read.