Colonial Hydroids. EDIT: What is this macro??

[ashwin1224]

My tank is now 25 day old and I intend to cycle it for another two weeks before testing any params or adding live stock. It is a 37g tank with a 14G sump. There are about 30-50 individuals of this creature in my tank. At first I thought they were colonial hydroids but they seem to be unlike any images I see of hydroids, mainly because they seem to be much smaller and they are not the same color. The creatures I have in my tank seem to have a brownish translucent tube and a white translucent head. They also dont seem to be bothered by light or any other stimuli. Attaching pic for reference:

Can they be some other kind of jellyfish poyps? Are they harmful?

 

The other critter is something I came across the second night I set my tank up, but never after that until now. Its very tiny, about 5mm max. Its got a yellowish tube like body and a crown with 6-7 tiny tentacles. It sometimes extends its body to as much as 1cm, but mostly it is compressed. Another thing, it showed up on its current location over night, it wasnt there a few days ago. I cannot seem to get a good picture of it since its compressed atm, but here it is( it is just below the tubes of two feather dusters):

 

EDIT: What kind of macro algae is this? Should I be concerned??

[Clown79]

Looks like a hydroid. I can't see anything in the second pic.

 

Are you testing ammonia and nitrates during cycling? Thats really the only way for most to determine if a cycle has processed

[ashwin1224]

I am pretty sure these are hydroids. Now, how bad are they? I am looking to keep a few hardy softies in the tank. Ive read that they go away on their own sometimes and that they are only really dangerous to dwarf sea horses. Are they really that bad that it justifies tearing the rock work apart completely and cooking it and restarting the cycle all over again??

[RayWhisperer]

I'm not too good with macros, but it looks like it might be Caulerpa racemosa. There seem to be several forms of Caulerpa that are identified as racemosa. However, the form Wikipedia uses (take that with a grain of salt) is a pretty good match to what you have. That being said, most folks seem to say the common names. And, the common name most associated with C. racemosa is grape Caulerpa, and the one I ID'd as C. racemosa, as suction cup Caulerpa. Then again, as I said before, I'm not too good with macros, so I could be completely wrong.

[Weetabix7]

39 minutes ago, RayWhisperer said:

I'm not too good with macros, but it looks like it might be Caulerpa racemosa. There seem to be several forms of Caulerpa that are identified as racemosa. However, the form Wikipedia uses (take that with a grain of salt) is a pretty good match to what you have. That being said, most folks seem to say the common names. And, the common name most associated with C. racemosa is grape Caulerpa, and the one I ID'd as C. racemosa, as suction cup Caulerpa. Then again, as I said before, I'm not too good with macros, so I could be completely wrong.

 

That's not a bad guess, but Caulerpa Racemosa grows from a runner and I don't see any runner there, they seem to growing directly out of the rock. 

The Macro that springs to mind for me is Mermaid's Cup or Acetabularia, which is a beneficial Macro.

 

The first pics do look like hydroids to me. 

[microworld]

colonial hydroids are not a problem, until they are a problem lol.  They are very hard to remove as they can can move deep into their tube like a feather duster. Pick them out while you have a few, they can reach plague proportions (not overly quick, but still)  They also irritate corals, however i have never lost any corals to them.