Help with ID of unknown string like lifeforms.

[shrimpnreefdude]

Any ideas what this could be? Growing abundantly on a heavily populated zoa rock I recently brought in. It appears to be a plant or algae at first glance. TIA

 

[WheatToast]

This is Bryopsis, a green macroalgae that is generally seen as a pest:
https://www.reefcleaners.org/nuisance-algae-id-guide
https://melevsreef.com/creature/algae-and-plants/bryopsis

 

[shrimpnreefdude]

This is Bryopsis, a green macroalgae that is generally seen as a pest:
https://www.reefcleaners.org/nuisance-algae-id-guide
https://melevsreef.com/creature/algae-and-plants/bryopsis

Thank you for the information. Looks like I'll be removing that rock later today and doing a bunch of zoa fragging because I'd rather ditch the rock than have to deal with that spreading.