What is this?

[torvall]

Hi everyone, first post and first attempt at a saltwater tank. I just bought a few small bits of live rock from the fish store, and I now have my first living being. Here is a pic of the little guy... (on the right hand side of this rock, opened up, yeah its blurry)

Anyone know what it is? When opened up its probably the size of a quarter and has small hairy limbs. It reacts to light and sound I'm quite sure as it recoils back into a small point.
Also, I have some other hitchhikers. The other guy is a dark brown and is very very small. It is maybe 1/4 of an inch wide and tall with round knobs on top. It has been roving around my tank for a few days and now I've noticed there is more than one.
Anyways, thanks guys!

 

[premilove]

from what i can see, its aiptasia. get a closer pic of it..
does itlook like this? if so get rid of it now. aiptasia X or joes juice. aiptasia x works better imo. aiptasia is a horrible pest. it will continue to spread until ur tank is covered with it.

 

[spanko]

First pic looks more like a feather duster to me. A picture of the top head on instead of side shot would help though.

 

[torvall]

Thanks for the input. The feather duster might be it, I was lacking a name and I'll get you a better picture later. It is off to the side of this particular rock and my cheapo camera is pretty old so I'll snatch the parents camera for a clearer one. Should I be concerned if it is a feather duster (noob alert!)?
I can definitely say that I have nothing in my tank to resemble the pictures of the aipstasia you provided, so hopefully I'll be safe.

 

[spanko]

Feather duster is a good addtion to the tank. It will filter nutrient from the water to eat.