What is this?

[JmeJReefer]

Looks to be aptaisia anemone.

couple of options to get rid of them...
1. Slush mixture of sea salt applied directly onto anemone via baster.
2. Aptaisai X chemical remover.
3. a squirt of boiling water on the site.
4. Peppermint shrimp (hit or miss)
5. Certain fish eat it
6. bergia nudibranch
7. cruise missile

the last one might cause a sandstorm...

[Slyguy00]

+1 for aptasia. Aptasia X works good and doesn't release tons of spores all over ur tank.

[pinkreef]

get aptasia x it comes with a syringe and a couple of different heads
it is easy to use and will get rid of the 3 i see. you have to sneak up on them or they will scoot into the rock.

[Misses.ReefWars]

slighly quicker way is sufficate it with coral glue or apoxy

[monza]

Personally I'd take the rock out and dig /smash around the aptaisia area completely removing it and any signs of it from the rock. Actually though, if it was me I would not even use the rock, it's a plague that may take years to get a foot hold but if it ever does you'll under stand. I see a few in your picture which means they can and probable are hiding every where in the rock.

[Magickiwi]

I use lemon juice in a syringe. The insulin syringes from a pharmacy work well. I haven't had one since my tank first started up.

[Cujo#31]

Cheapest and easiest.....go to Canadian Tire, head to paint department and buy a 9 dollar bottle of Muriatic Acid. The stuff works awesome.

[mark]

if you're looking for fish suggestions for your FOWLR, could consider a tile fish. Not that big, little strange looking, follow you around the tank plus eat aptasia.

[EdsonFOWLR]

Originally Posted by mark

if you're looking for fish suggestions for your FOWLR, could consider a tile fish. Not that big, little strange looking, follow you around the tank plus eat aptasia.

You have a scientific name for the tilefish?