Whoa... Can't say I've seen anything like that before. It's interesting, though.
Now, in Map Maker, are those colorful dens intentional, or were they meant to be stone? I have a feeling that the material files for those are corrupted.
OR, if not that, try to put the colorful dens into a different object (.fho) file. So, if you have My_Stuff.fho, make a new one (we'll call it My_OtherStuff.fho), save the dens into the OtherStuff file, and replace them in the map.
I hope this'll help you a bit.