I absolutely love this. The texture on the raised bits gives a strange organic/metal look which contradicts itself in a very interesting, yet pleasing way. The colours you used all work to further this image, the coldness of the blues offsets the almost mouldy look of the greens and it's all balanced out by the earth/rust brown background. On the subject of the background, however, comes the only negative I see in this piece. The main background is too uniform, all being one shade of one colour. I think it would improve the work no end if you added patches of different shades of brown.

All in all, very well done.