Resolved What is growing on my rock??? Answer: Homotrema rubrum

My daughter pointed out some things she found on a rock in our tank this morning, and I need help with its identification. For the record, my tank was born 7/31/10, but I restarted the cycle by adding formerly live rock approx. 2 weeks ago. Here is what she found:

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It looks like coral growing to me, which would have me puzzled. There are 3 or 4 of these growing in a hole in a large rock I have. The hole is approx. 4 inches across if I had to guess. The rocks I added were formerly live, although I am unsure how long they have been dried. I had 1 piece of true live rock that I added and had live sand as well.

So detectives... what is growing on my rock???

 

Does it look like

If so, it's a feather duster.

 

Bloodkip, I blew the photo up more for a better look. It looks like a branch and not a tube like a feather duster. (See photo)

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looks like some type of a macro algea

 

Appreciate the reply. I Googled Macro Algae and found some images that look similar. Looking forward to more opinions as well.

Let me add that these are very small right now, the biggest being less than 1/2".

 

Foraminiferans:

Foraminiferans by Ronald L. Shimek, Ph.D. - Reefkeeping.com

 

Hmmmmmm I'll have to read over that article later today. The photo looks like what I am seeing in my tank.

Are foraminiferans harmful or beneficial to sw aquariums?

 

They are safe, don't know about them being beneficial or not. Having them means you have good water quality.

 

Considering I'm still cycling my tank I'm not sure how good the quality is right now. I'll have to check the levels again today and see how I'm doing.

How big will these get? They are at a bad place if they get large, as they are sitting in a 4" hole that goes through the rock.

If everyone agrees this is what I have I will mark the topic resolved.

 

Also curious if this is something that spreads easily and could overtake the tank.