Letting algae grow into decoration?

[BassetsForBrown]

Hi,
When I setup my tank 3 years ago I constructed a nice looking rock structure. I've never scraped it, and in that time algae has grown over the tops of the rocks into what looks like paintbrush bristles. They're about 2-3cm long, and are a green, maroon, and purple in color. I love how they look moving with the water, but was wondering if it's safe to keep them with my Oscar?

I don't get much algae otherwise, the small amount on the glass I just scrape off every few months.

I'm not home to take a pic, this one from Google is the closest looking to the type of algae I'm talking about:

 

[BassetsForBrown]

The algae in the pic looks exactly like what's in my tank, but my covers the ENTIRE rock, not just patches.

 

[FriedFlowerHornFillet]

I like to get sculpture. Usually a bust like the head and shoulders of a person and then I remove the algae from every area but the hair and beard. People always love it.

 

[duanes]

I always let true algae (like the kind in your pic) grow on rocks, and back and side panels, I find it is great grazing material for fry, it helps consume nitrate, and I also like the way it looks.
I do not let cyanobacteria grow, if I can help it.

 

[Gourami Swami]

I have plenty of that kind of algae in my tanks, I try to keep it off the glass but I let it grow freely on my driftwood. It's fine to have in the tank

 

[GamerChick5567]

Looks like black brush algae, I have seen it get that light in color. It's perfectly fine if you want it but it sometimes is a pain to get rid of if you don't. Leaves are sometimes annoying to clean. The good news is siamese algae eaters will eat it. I let them do all the hard work haha. Some snails will and I have seen my guppies take an occasional nibble but they don't usually touch it. If your oscar or a tankmate eats it I wouldn't worry.

 

[markstrimaran]

Ya beard algea, come in green, black, and red. I encourage it's growth with marine reef lights., my 30plus mbuna keep it trimmed pretty short. Seems to keep keep them occupied and out of trouble.

 

[neutrino]

I always let true algae (like the kind in your pic) grow on rocks, and back and side panels, I find it is great grazing material for fry, it helps consume nitrate, and I also like the way it looks.
I do not let cyanobacteria grow, if I can help it.

Pretty much what I do, also on driftwood, which is where I like it. Any species of fry I've raised will graze on it, including my kapampa fry.

 

[BassetsForBrown]

I finally got home to take the pics below:

 

[BassetsForBrown]

My biggest concern is that the algae has been green/dark green for 3 years, and in the past few months it has changed to that purple/reddish color for some reason.

I like it, but have no idea why that happened.