Tank Became Really Really Brown!

I got some eggs on the glass for 2 weeks. Nothing came out yet, while those eggs become bigger with empty inside, but I believe they are not fish. One morning, when I turned the light on, my tank became really really brown. The brown is all over the tank: on glass, on stones, and in the water. Is the brown from the plants or some live animal in the tank? I cleaned some brown when I changed water. It is like the brown things I saw in bathroom table where water is seen for a long time.

The platies eat those brown things on the glass, and gave black shit, like the shit they have when they eat plants. They have white shit when eating bread I give them.

P.S it is a 10 g tank, with 2 platies, 2 zebra danios, and 1 chinese alge

My tank once had some algae growing on a rock, which was deep red/brown. My pleco ate it up like any other algae. I have no idea why it appeared, and I haven't seen it since. This could be what you have.

Could it be some kind of algae you are seeing? It sounds like it's sprung up really fast and it's on every surface but it's not actually colouring the water. Is that right?

Have a read of http://www.thetropicaltank.co.uk/algae.htm which I found in google, specifically about brown algae. Hope this is of use to you.