Whats is this and whats next?

I am still pretty new to this hobby. I have a nano tank but to be honest I did not pay much attention to details and now that I am going to a 55 Gallon, I dont want to miss a thing.



This is sorta week two or about to be three of the cycling of my tank.

I noticed yesterday just a very tiny small of this sorta stains on my rocks and today they are very noticeable. I just wondering if anyone knows whats going on.

I used two small live rocks ( they hidding on the back) to help cycle my tank with dry rocks.



Thank you so much guys and hopefully someone can tell me what comes next.