Is this algae, sponge, or what?

[fishphreak]

I have recently noticed this flourescent green spongy looking stuff on one of my rocks and it since spread to 2 more rocks.
Does anyone have any idea what this could be? Is it harmful?
Any info you could offer on this would be great!
Thanks in advance,
Jessica

 

[fishking]

dont know wut it is so.... bump

 

[stangbabe1993]

i had something like that growing on the back of my cup coral it was more yellow and bigger bout the size of a small egg and spongy. don't know what it was either

 

[clarkiiboi]

Not sure, but if was me I would be concerned if it is spreading fast. How long did it take to spread to the other rocks? Looks like a sponge, but never had any spread.

 

[fishphreak]

I don't really know how long it took to spread. I just sorta noticed it one day when I was searching every possible spot in my tank looking for my Nudibranch (aiptasia eating nudibranch)that I hadn't seen in 3 days.
The 2 new patches I found are really really tiny about the size of a dime or a little smaller so I don't think they have been there very long.
This is my first saltwater aquarium so I am extra paranoid about things in my tank that I can't ID.
I have been searching the internet all day trying to ID this thing and I can't find anything even close to this.

 

[fishphreak]

I don't know if this will help or not but I noticed the first patch (the one in the pic) about a week after I upgraded from flourscent lights to pc lights.

 

[causeidm]

Looks like an alien to me

 

[gkp]

Looks like a yellow florecent sponge to me. I have had many in my tank......Look for a single tube coming from it rarely they have two. If it has this tube it is a sponge.

 

[erikandstacie]

I'd say sponge as well...

 

[fishman830]

touch it, how does it feel?

 

[fishphreak]

The big one doesn't have any tubes that I can see.
I found more spots of this this stuff. 4 spots in all.
They are the same color and as the the first one (the one in the picture) except they DO have tubes.
2 patches have 1 tube each. And there is another patch that looks like it has about 8 tubes.
Is this somthing totaly different or do they simply look a little different because they are smaller?

 

[fishphreak]

I just touched it and it does feel kinda spongy.