If you are talking about the Petco Fiji Aquacultured live rock, I brought this up a while ago. Anthony Calfo had a bunch of slides showing these facilities. Fiji Aquacultured LR is made by blowing up the reef, harvesting the calcium carbonate, taking it to the cement plant, which they build virtually on shore, and creating the donut shaped rock.
In Fiji, there is a limit on the amount of actual lr that can be harvested, but there is no limit on how much reef can be blown up to harvest calcium carbonate.