No, you are correct when you say it all becomes alive. I did this because later when you get that fish that swims to the bottom and decides to stir things up a bit with his tail, he won't disrupt a large amonia pocket that often times forms under the larger granuels of live sand found in LFS tank bought scoops of LS. In my picture, you see the tank bought LS underneath the crushed aragonite. It all ends up being alive, but the pockets are much harder to disturb this way, and the bacteria ends up taking a stronger hold in these little "caves."