white stringy algae?

[jburns]

i ordered new rocks and gave them a light rinse before adding them in and noticed this stuff all over the top of only this rock which isn’t even the highest in the water column. what is this stuff, how harmful if at all is it, & how do i get rid of it?

 

[Barliman]

Is that a saltwater or freshwater tank?

 

[jburns]

Is that a saltwater or freshwater tank?

freshwater *rocks are claimed freshwater safe in case you’re wondering*