What are these on my star polyp rock?

[brettmontgomery]

I got a rock with green star polyps on it and there is a few of these on there.

 

[Sniperhank]

Looks like aiptasia to me. A pest glass anemone that can spread quickly. They need to be managed with a product like aiptasia-x or being injected with boiling water or lemon juice. If they are pulled off, they will 'shatter' and spread tons of spores around the tank, hence the glass anemone name, and start up where they land as new anemone.

 

[DadE02]

From the photo, it almost looks like the rest of your star polyps--can you get a closer photo or one with a different angle.

Aiptasia multiple fairly quick. Good thing aiptasia-x works great and is easy to use.