What does ____ stand for?

[mckeec]

I have seen/heard the tern RNT or maybe it was RTN used to refer to a unhealthy coral. What is this?

 

[Swanwillow]

rapid tissue necrosis

its when the tissue on sps/lps just starts to... die. usually from the bottom, but can happen from the tips

 

[mckeec]

Thanks, I figured something like that.