Please explain this to me

[BlackTip]

I have few SPS frags that I bought from a member here. They have been in my DT for almost a month. 5 of them never opened up, and 1 has STN. It started at the tip, and slowly the top 1/8" became white.

Last week I had cyano outbreak, so I decided to do a 3 days blackout. Today I turned the light on, and to my surprise, 3 of the frags that never opened has coralite extention, and the frag that has stn has coralite extending on the white skeleton.


How is it possible?

 

[Acronic]

Just the tip? ��

Maybe they just got bleached out?

 

[Ricardo Fonseca]

In the lack of light there's no feeding trough the zooxanthela algae therefore they need to prey. They do so by the polips, traping small particules on the watetr.