Hi everyone,
I've been pixeling this floor tile for a platformer that I'm working on with a friend.

Which I re-purposed out of this concept that I made earlier. (we've change the color scheme of the cave since I made the concept, also the hallway is my friends handy work)
http://i1218.photobucket.com/albums/dd409/freudianSLAP/UndergroundConcept.pngNow I like the general feel of big clean ambiguous forms that the rocks in the concept have. However, when I try to shade the rocks in the tile it completely loses that quality.
I've tried about 4 different variations of shading and color but in the end came back to what you see here in the floor tile.
I would really appreciate if someone could point me in the right direction with making theform of these rocks more obvious. With out making a bunch of pixel noise the way I have with my attempts

General C+C on the tile is also welcome.
Oh almost forgot, my original inspiration for the concept piece was this concept image from Cave Story 3D
http://i1218.photobucket.com/albums/dd409/freudianSLAP/First_Caves--article_image.jpg