Finally got through your thread, nice work and really like the pyramids. Do you remember any problems with them and any of your corals?
Do you have a quarantine tank? I'd remove them all to quarantine. You might have a hitchhiker, or a water problem, or maybe one of your fish is picking at them when you're not around to see; at night, perhaps.
If they get better in quarantine you know to start looking at your display tank. If there's another problem, like pyramidellid snails, then they will probably show up easier in the quarantine tank.
Dave.M
Have only lost two corals since setting up this tank. One was a piece of acropora that died for no apparent reason, the other an open brain that got nipped by my Flame Angel.
I have a long thread on the pyramids in the Reef Fish forum. Details my trials and tribulations with these fish.