A Lot Of Us Use Tufa Rock Or Other 'non=live' (not Fake-its Real Rock!!)
For The Base Because Live Rock Is So Expensive And Because It Just Gets Buried Underneath. As Mentioned Before, Over Time, The Base Rock Will Populate With All Kinds Of Stuff!
Do Be Careful About What You Use For Your Base Rock, Though. Tufa Is Best, Lava Rock Is Not Safe As It Is Loaded With Debris And Contaminants.