The polyps that you lost may attach themselves to rubble in the bottom of the tank. When I received my corals, some lost polyps. I was able to gather some, others were out of reach. They drifted around until they found a place out of the flow and attached themselves to rubble. As time passed, I think my crabs moved them out from their hiding places as they did their little crab thing.
Yesterday I was able to gather 5 different polyps and attached them to larger pieces of rock. Some had attached themselves to rubble that was actually smaller than their base.
