White spot on red Montipora Plate

[Tim'sReef]

Hi all,

Today I noticed this white spot on my red Monti. It has been growing well past 2 months, I hope this isn't due to monti eating nudibranch but just to be sure I dipped it in coral RX.

Parameters are all fine except that my calcium is a bit low around 360 while it is usually around 420 (coral box doser doens't want to keep the line primed :( ) Other corals including my green montipora plate are looking fine. What could this be and what would you guys and gals do?

 

[Tim'sReef]

 

[findingsimple]

What ended up happening?

 

[Tim'sReef]

Unfortunately it was nudibranchs they destroyed that one and my green plate. When I upgraded my tank I got a piece of the green all clean and growing that out currently.

But man I don't want those little white nightmares in my system ever again.