This mod adds a variety of cool blocks that camouflage themselves to the surrounding world. All of these blocks have extremely useful functions that allow you to simply hide your diamonds, or punish all who dare try to get to them. Hidden doors, pressure plates, hidden levers and more! pay special attention to the revolutionary Ghost block. this block is visible in every way, but you can walk right through it. A fearsome trap for anyone who dares try stealing your diamonds with a floor made of this stuff over a pit of lava.
For more info, see the MC forums thread.