Well... they don't quite scream evil invasive tree roots to me. But it's an interesting concept, and the overall map looks pretty cool. I'd suggest searching "uprooted tree" with Google Images. Or just look at this one: File:Uprooted tree 001.jpg - Wikimedia Commons Note how many smaller roots are growing off the main structures and twining and twisting insidiously throughout it all and just making a really gnarly mess. It's not something I'd want creeping around in dark tunnels seeking out my warm flesh to feast on.