I'm afraid that I have to agree with the comments about slime.  Still, your atmosphere isn't bad, and it's certainly a good concept.

I thought some sort of slimes were consuming them, no offense! It doesn't look much like ice.

I see some sort of dark gray liquid climbing up the pyramids. Perhaps you should try a significantly brighter palette for the ice, like this: http://www.pixeljoint.com/pixelart/42277.htm

Counting your colors accurately is quite easy: http://dpmm.110mb.com/CKinesis/ColorCounter.html says there are 15.

15 colors. (To be picky, there are some colors that are very samish...so, you could easily make it 13 )

I think the snow/ice is a little too blue? Anyways, good luck in the challenge.