I have noticed that corals seem to take a little longer to grow onto the ceramic plugs. They have a very smooth finish, which doesn't allow the coral to properly bond to the surface, IMO. Also, the ceramic tiles are very strong, but not worth the price, again just my experience. I have had great luck with making frag plugs from home and just selling them or trading them to fellow reefers in need. If you are looking for some, I might be able to help you out. Hope this helps!