Just to help, if you do see the monti nudi's, they are tough to treat. The thing that worked for me was a melanarus wrasse. Other people say the green or yellow wrasses also eat them. Never tried those myself.
Its brutal, they hide under the coral during the day and come out at night. I lost giant monti caps in just a few weeks with those pests. No meds worked at all!! It really does look like that picture...I will not be surprised if they are there.
+++1 nudies, tough to beat. if you have other monties I would pull this one and try to qt it. And yes check at night. You must kill all the adults so that they cannot lay more eggs. dips don't seem to work on the eggs.