But can you dense pack with it?

Two Rensselaer Polytechnic Institute grads are trying to turn a part of mushrooms into an insulation material.  Not the whole mushroom, just the mycelium. 

I don't know, just something about mold in a house seems funny to me.  I know it isn't really mold, but a part of the mold. 

The new start up, Ecovative Design is working on a SIPs-like product that has some filler material between the structural panels.  The mycelium feeds on that filler, growing in to fill the space while leaving behind a stronger, somewhat foam-like insulation behind.  Only there are no blowing agents involved, which is rather un-foam-like.  No harmful VOCs to off-gas!