what algae or plant is this?

[waynel]

I have this green, almost feather like, green algae growing in various spots, and nothing seems to eat or touch it:

 

[vetteguy53081]

I have this green, almost feather like, green algae growing in various spots, and nothing seems to eat or touch it:

Appears to be bryopsis which is the bear of algaes.
Can you take another pic under white light to confirm ?

 

[monkeyCmonkeyDo]

I agree looks like bryropsis. White light pic will help though.
D

 

[damsels are not mean]

Bryopsis. A few ways to deal with it. The least elegant but perhaps most reliable way is to rip as much out by hand as possible and try to cover all the spots it was with something like gluing a sheet of something over it until it's completely dead. This way can eradicate it in a tank if done properly. It is important to note that bryopsis roots itself in the rock and can grow back even if it looks like you got rid of it. Keeping it contained and getting ahead of the issue helps a lot as it doesn't spread too fast unless you just let it go.

Some people report success just squirting small amounts of peroxide on it to weaken it which makes removing easier.

#3 is somewhat experimental, but apparently these slugs eat turf algaes including bryopsis. Whether these claims are true seems to have limited conclusive evidence but it's worth a try. They are also easy to care for and will reproduce as food is made available to them. They are much more rugged and hardy than lettuce nudibranchs or dolabella sea hares and stay very small.

Jellybean Slug (Onchidella floridana)* — The Wyld Zone

A very durable and unique slug capable of breathing air. This species will readily consume most algae including turf and bryopsis. This species is safe to handle outside of the water.

www.thewyldzone.com

 

[EeyoreIsMySpiritAnimal]

Fluconazole usually works for bryopsis

 

[waynel]

More pics under brighter light