By laying on the ground do you mean off of the skeleton? It sounds like Polyp Bailout.
Polyp Bailout is the action of the coral ripping the fleshy tissue from the hard skeleton
In my experience with Polyp Bailout is it is normally caused by fluctuations in water chemistry, especially alkalinity, to much flow, or stray voltage.
A few things we are going to need to get an accurate answer for your questions are: water chemistry
Salinity
PH
Temperature
Ammonia
Nitrite
Nitrate
Phosphate
Alkalinity
Calcium
Magnesium
We are also going to need lighting and Flow, was their any recent changes?
How old the tank is, current inhabitants, algae issues?
-Zack,
