Live rock in the truest sense of the word is fragmented pieces of old coral reefs that broke off during storms or by wave action. These pieces then washed into shallower water where they were naturally colonized by marine life such as invertebrates, corals, sponges, and millions of beneficial nitrifying bacteria. Live rock can be found anywhere in the world's oceans where natural reefs occur. Live rock from different regions have slightly different characteristics including form, density, porosity, as well as the type of organisms that colonize them. However, all live rock is beneficial in providing supplemental biological filtration, increased biological diversity, structure, and shelter.