Newbie Here = Be Nice

I know this is a very common thing in salt tanks, but I don't know the name, I think it could be something that would harm a reef tank (just cycling my tank now).

 

Aiptasia, kill it immediately, it can take over your tank quickly.

 

How do I kill it? Just scrap it off?

 

you can but get all scraps of it, if a scrap is left it will grow another one. So basically you must take the rock out during the process.

you can also buy stuff like joe's juice and inject them with it to kill them.

 

+1 on Aptasia. And +1 on KILL IT NOW! lol.
Pepermint shrimps will normally eat them, but seeing as you only have 1, and quiet a large one, i would take the rock out, and scub it off with a new tooth brush, or buy a a paste designed to specifically kill aptasia, and of course as sostoudt said about injecting it with juice

 

+1 to aiptasia. Kill it.

 

Take the rock out, scrape as much off as possible, then cover the area with kalk paste before placing it back in your tank. Or do what I have done in the past: Inject it with near boiling hot lemon juice (right into it's mouth) if you have a syringe handy. It melted away and none have ever returned.

 

Welcome to the site and as mentioned above yep its a problem! LOL Guess no need to tell you how to fix it as there are many ways already mentioned.

 

Aiptasia and Mojano Anemones represent a very prolific pest in the marine aquarium world. They grow rapidly under less than optimal conditions, are very potent in terms of their sting(nematocysts) and WILL sting anything they come in contact with.
Their are many ways of trying to rid an aquarium of these animals! Vinegar, Joe's Juice, a Kalkwasser paste solution, lemon or lime juice, hot water or removing the rock or coral from the tank and scrape off the anemone from its foot.

Peppermint Shrimp as well as many species of Butterfly fish will consume these and help to keep them under wraps. Butterflies such as the Copperband and Longnose will feed on them but are not what you would consider as being reef safe fish.
Unfortunately these animals don't make a welcome addition to a reef aquarium since they are great filter feeders.

 

It is definitely aiptaisa... I had the same problem and as there are many ways to treat it ... I used vinigar... make sure it doesn't spread!!! It really can do a lot of damage once you get corals in the tank.