That is a nudi..I'll take a leap and venture that you have orange zoas in your tank..yes?
Zoa eating Nudi's 'become' the color of the zoa they have recently/are actively eating, thus making them SO much harder to see.
If you have one in your tank, there is an excellent (sorry!) chance that you have more. Best option is to dip ALL of your zoas in Lugols Solution, and carefully inspect every colony for their eggs.
The eggs are IMMUNE to the Lugols Dip and must be scraped off..the only way to get rid of them.
Not that I know of, and if there is, you can't guarantee that it will go right after them. Nothing will be faster than manually removing the ones you can see from your tank. Dipping every zoa frag/colony is very important!! The Lugols will knock them right off zoas very quickly, and then you should inspect each polyp for any egg masses.
Tomorrow I'll see if I can find the pic of what the eggs look like for you.
Remember, they can munch their way through zoanthids at an amazing speed and they also reproduce fairly quickly.
A good portion of the Halichoeres sp. will nip at if not kill a good portion of nudi and other pests, always a good reef safe addition to any tank and great for pest control.