They're used for beach erosion control and making new reefs:
Reef Ball Foundation: Getting Grants For Your Project
my approach is a little more for current issues as opposed to years of building reefs,
having been here for many years myself and having a Dominican wife and baby I don't really have time for games yes I have been involved in many reef projects in japan Bohol php and Hawaii. ,I offer a solutions to a variety of sea problems. im not a tree hugger looking to rebuild the ocean here,
however the damage that has been caused by years of debris dredging and the like are not of my concern and would take many more years than I could live in two lifetimes to repair.
I do see however that many homes and hotels have wave ebb and flow issues that could and should be addressed.
that being said. I hope this clears the view and perhaps puts directness in to the equaision..
sorry for not paying for advertising my plan was to do so Monday.
Patrick..