What's this?

[Gorilla4200]

Anyone know what these are? Thank you

 

[flsalty]

Spirorbid worm. Harmless feather duster type worm.

 

[El_Guapo13]

+1 on spirorbid worm. Harmless filter feeders. I have hundreds of them on my rockwork and in my backwall.

 

[Gernader]

+2 to @flsalty . I have some of them in my reef tank and they are rapidly reproducing, so I recommend you to clean the glass more often to keep the population down unless you don’t mind having too many of them lol.

 

[Gorilla4200]

Spirorbid worm. Harmless feather duster type worm.

Thanks guys