They are ceramic. You don't need to "cure" them but they do go through a cycle. They are not like liverock where you get a big amonia spike and they stink up the house. But there is zero life on it when you start. It takes time for the bacteria to colonize. Once this happens it will start to color up to match the look of your rockwork in the tank.
We use the purest clay we can find that still works with our process. But clay is still an organic substance and it does vary. If you were going to put a piece this large in an existing aquarium I would save your water change water and let it run in a container for a few weeks with a powerhead and heater to get the bacteria started. If your starting from scratch I would just put it in the tank and add a bottle of bacteria to get it kick started. Do a water change every two weeks and then start testing your parameters to get measurements. Just liek a new tank you want to keep light to a minimum to avoid an algea bloom.
Our structures usually turn a dark green in the first few weeks to a month. Its diatoms feeding on the ceramics. If you have a heavy coralline population it will start to grow coralline fast. If your starting from zero it will take more time.
We are about to set up a 93 gallon cube at the LFS in hopefully the next week or two. We are going to plumb it into the existing coral system so it gets a kick start. It will be a 100% ceramic reef. We are going to display it at macna this year and then donating the system to a special needs classroom in Iowa. We are letting the local reef club determine what school it will go into. Here are some pictures of the aquascape and tank dry. The store is doing a rebuild of the fish system and once they are done it will get set up. It doesn't look like much now but once it is covered in coral and coralline it will look awesome. We'll be taking progress pics every couple of weeks.