Okay, first off: I'm a mole. I LOVE being a mole underground. And now, after finding cubic chunks, I'd like to ask if Terraformers work underground so I could "grow" sand for my sandstone tombs and perhaps grow trees underground using the cultivation. If yes, then this would be the ULTIMATE means of becoming a mole! I WOULD NEVER SEE THE SUN EVER AGAIN! CURSE YOU, SURFACE DWELLERS! 
(Crosses fingers) I hope it does work undergound, or will in IC2