usa

Since 1999, a ready mixed concrete unit of RMC South Florida Inc (a subsidiary of US holding company, RMC Industries Corporation) has provided free resources to local ecologists and the Marine Studies Program of a local high school to manufacture "reef balls". Using a special concrete, coral can be planted on the outside to provide a natural reef habitat so that coral and fish populations that have disappeared at three locations in the Upper Keys can be restored. Around 180kg of animal and plant life attach themselves each year.
http://www.reefball.com/