What is this

[Juice780]

Is this coralline algae staring on my back glass? It’s white so I wasn’t sure. I used a bottle of arc a couple months ago.

 

[Crabs McJones]

Are they hard? Looks like spirorbid worms from what I can tell.

 

[Juice780]

Yes they are hard. It’s growing. What ever it is.

 

[Juice780]

Anyone have any idea? It seems to grow in a spiral. I hope it’s nothing bad.

 

[Juice780]

Looks like you might be right crabs. Are they bad?

 

[Samina]

+1 with @Crabs McJones. Looks like spirorid snails

 

[UCF Alum]

@Juice780
Can you take a better pic?

 

[Samina]

Filter feeders. Their population kind of self regulates. You can scrape them off if you’d like but they are not bad for your tank.

 

[Juice780]

Here is a little better pic.

 

[stanleo]

I agree they are spirorid snails. I have them all over the back wall of the tank. I like how they look.

 

[Mikedawg]

if the bother you, just wait and they'll usually go away; if you can't wait use a plastic credit card to scrape them off. They are a vaulable part of your tank's biodiversity IMHO

 

[TheShrimpNibbler]

They’re spirorbis worms. As others have said, they are harmless. If you look closely, you can see the feather like things they use to filter the water.

 

[Juice780]

Will that prevent my gsp frag from covering the back glass like I want.