Id

Danger?

 

Don't know about the first one but the second looks like a feather duster or maybe even a coco worm. Most likely feather duster.

 

Nope. First is a sponge, second is a feather duster

 

Do they pose any threat?

 

Yes, they threaten to make your tank look cool and act as a natural filter. ;D

Just kidding, they're great to have.

 

Very nice man! I wish to find something half that nice in my stupid rocks
they were cured so i didn't get a whole lot with mine.

 

No sorry guys and gals first one is a macro algae, either Scinaia complanata or Solieria robusta
Got lots of it in my 16, only this one has lost most of its color. Here is a photo of mine.
Oh yea, it poses no threat, it is very easy to control and slow growing.

 

I didnt notice the sponge until I put in a halide light and now there getting big and I see there growing on top of my maxi flow pump.

My rocks dont have any color to them. It has some pail green color to it but still no coralline algae.

 

I'm with gazog!!!

Their aren't any syphons for it to be a tunicate or sponge!
macroalgae! A good thing!

 

Sorry I got a new camera yesterday.