Strange algae (?) in my sump

[Dash]

I was doing a bit of maintenance in my sump, taking out some hair algae, and found a strange plant form growing on the rock. This is not one of my original live rock, but one I got from a LFS not too long ago and perhaps unwisely put into my sump. They are upright in the water, and the larger ones look like white segmented worms. I found a couple of photos in Google but no info attached to them.

Friend or foe?

https://farm5.staticflickr.com/4786/39934889294_b5e9e77f97.jpg (https://flic.kr/p/23QUKh3)
https://farm5.staticflickr.com/4801/38834532080_667f3f5eaf.jpg (https://flic.kr/p/22aF8pW)

[DKoKoMan]

Ahh what are those!? Looking to see this identified. I do recall Big Al’s LPS tank to have all these weird things on their LR. I have not bought anything out of this tank after I saw those present.

[Dash]

This rock was in a bucket for a couple of months prior my tank transfer, looked perfectly innocuous. One month under the sump light, and it’s Invasion of the Bodysnatchers:confused:

Hope it’s some awesome macroalgae that eats phosphates for breakfast

[DKoKoMan]

Lol... if it is I will be getting some of those alien looking things for my tank.

[H2o2]

I think its called Banana algae Google it

[Dash]

Thanks H2o2, I think you got it.
Neomeris annulata, or finger algae. Many report it as invasive (thrives in SPS tanks). As it’s calcareous, nothing will eat it. It also is inefficient at nutrient export so is useless in the sump. Since it spreads by fragmentation/sporulation, I think it’s best to remove the rock. Luckily it’s just a small random one that I tossed in the sump for the pods so no big deal.
Weird that it requires calcium to grow & I don’t dose anything. Apparently some people want it in their aquariums, in which case it’s recommended to supplement calcium. If anyone wants this, they’re welcome to it, haha

[Myka]

I've never had that algae become invasive. Not to say it couldn't be.

[Dash]

Just to follow up, I decided to keep the rock & observe this algae's growth. It spread quite rapidly, from about a dozen heads to 30 or so in this 3-week period. They are attached quite firmly & are difficult to remove so I can see them being a real nightmare in someone’s DT. Quite a few big mature ones which are filled with gross white goo. I picked the rock as clean as I could & returned to sump - interested in seeing if they will return.

[Myka]

Thanks for the update. :) surprising they grew so fast.