Live rock on eggcrate, sand or on bottom?

[born]

I laid egg crate on mine. Did it so I knew my rock would really slide since I was building tall islands and didnt want to all of a sudden have my islands collapse. But if you do eggcrate make sure you have plenty of sand, cause if you dont it limits you to certain sand creatures. Like pistol shrimps, jawfish, sand sifters going through the sand.