Is this normal?

[Y0U]

Good morning reefers,

I would like to know what this is growing or attaching to the back of my display tank. Over the past weeks I’ve been noticing more and more of them. I did scrub at one with a toothbrush and it sort of flaked off without much trouble.

What are these?

Should I do anything about it?

Thanks in advance

 

[tzabor10]

Vermitid snails perhaps

 

[rayadog]

Definitely some sort of sedentary gastropod/snail or filter feeding worm. Don’t fret. And also don’t fret if you have to scrape the back glass to clean it at some point as the tank matures. They come off easy and will likely populate back.

 

[saltwaterfish.com]

Very normal and expected. One of the first signs of life on the journey of cycling a tank. Enjoy the ride.

 

[Crabs McJones]

Looks like fan worm tubes

 

[ISpeakForTheSeas]

Looks like fan worm tubes

+1 for (most likely Serpulid) feather duster worms; harmless filter-feeders.