Looks like sediment that has just stuck to the sides, i would also guess its nothing to be concerned about. Fermenting for 2 months ???? are you sure its still fermenting ?
check the sg, and i think you will find thats its done and you should rack it and leave it to clear.
Looks like yeast to me. I had yeast rafts like that in a batch of Ordinary Bitter that I pulled out the first bottle for tasting yesterday. They collected on the little grooves along the inside of the Grolsch bottles I used. Tilted them slightly each way so it fell to them bottom and then chilled. No problems.