“Live Rock” is actually neither “live” or “rock”. Live rock is the calcified skeleton of a once-live coral. Powerful tropical storms pound the coastlines of islands, and in some cases, continents, i.e., Australia's Great Barrier Reef. What was once a living coral reef is reduced to rubble as a consequence of tidal surge and pounding waves from the storm.

The corals living in these pieces of broken reef die off and the calcified skeleton that is left, decays. Over time, it becomes home to numerous bacteria, algae, worms and microcrustaceans. This “Rock” is now “Live”.

The millions of creatures that inhabit the rock form the core of the biological filtration method. The rock and sand are the filter. Without live sand or live rock, keeping an aquarium clean and in balance would be a continual struggle. This material, if it were not harvested, would eventually decay further and become coral sand (or worse, crushed and used to pave local island roads!). Our devotion to the use of live rock is all part of our attempt to replicate nature, and when we do it as faithfully as we can, the “system” works, makes maintenance minimal, and for the most part, takes care of itself.

This is a renewable resource, and in a sense we simply emptying "nature's trash can". There are alternatives however, and it is possible make your own live rock... An amazing institution in Idaho called GARF (Geothermal Aquaculture Research Foundation) strongly advocates this process, which is a process of using coral sand (aragonite) mixed with mortar. You can read all about it here.