Aiptasia?

[Endless Ocean in My House]

These little white guys popped up on my LR. I haven't had that piece of LR for a very long time, and not long after I got it I noticed one little anenome growing on it. I ignored it and it disappeared.
Now, there's this. On the other piece of LR there's something like hair growing on it, and slightly in the back of my tank--I thought that was just a build up of algae and I wiped it off, but now I'm not sure.
Is this Aiptasia?
And if so, how do I fight back?

 

[Mrc8858]

Looks like a pineapple sponge

 

[crister13]

+1 pineapple sponge.