White dots on glass

[murphy’s reef]

I’ve noticed these little white dots with little arms or something coming off them, they seem to be multiplying. Can anyone tell me what these are and what i should do ?

 

[Duffer]

Hydroids...

 

[murphy’s reef]

Hydroids...

any advice …..

 

[Duffer]

They can sting fish, most times they are harmless...they should go away by themselves

 

[murphy’s reef]

They can sting fish, most times they are harmless...they should go away by themselves

thanks man !

 

[Buckster]

One of my tanks is loaded with them. I think it is time to scrape the glass!