something is wrong with my rics

I have an oyster and it had a crap load of beautiful rics on it's shell, when it was purchased I thought it was a rock...a movin rock turned out to be an oyster. Well recently my rics have fallen off, shrunken up, and going white! My perameters are fine, I do water changes every 2 weeks since my biload is lower now, nothing has been added or changed. Everything else is growing, and growing and lookin great besides these. Anyone have any ideas as to what I am missing here?

 

Sudden change in light (placement in the tank) ?

Rics are IMO usually not very hardy for change

 

Nope, been in the same spot since a month after I got them which was a long time ago. Lighting the same, no new bulbs and the fixture was purchased in january. No new additives, everything is the same, it baffles my mind.