definately a monti nudi. looks like a full grown adult, which means there is probably many, many more to follow.
I ended up getting one adult in on a frag once, and it ended up laying eggs. Lost The one adult almost took out an entire hand sized red cap by itself, and when the babies hatched they wiped out my superman frag. I had to pull the superman frag and throw the whole thing out, because they were all over it, and I had to cut away almost all of the red cap and was left with one dime and one 1/2 dollar sized frags.
I suggest quarantining all your montis, dipping with lugols or something similar, and cutting away all the affected areas.
Its sucks , but that's how I had to get rid of them.
Hey went out and bought a Whovens Wrasse, hope I spelled that right?Did not do the Job pretty fish thogh.SO got some corall dip from Tropic Marin Pro-Coral Cure!!! Holly S#$% you should see the critters that came off it .... I have them swiming in Rubbing alcohol So when I buy A microscope I can see what I have,and DISECT IT FROM THE INSIDEOUT
when dipping it will drive the nudis out of there hiding spots. I make the solution so it is a very dark tea color. Then I take a turkey blaster and blast them. At this time insect for eggs under the montis. If you find them use a soft tooth brush and remove the eggs. The reason for redipping is for the nudis you missed and the for the eggs that hatched.