What's this?

[crosseyed]

I have some yellow growth on my live rock. It just appeared about a week ago. The live rock has been in the tank for about three years but I just recently started to add corals to start a reef tank. The yellow growth has a "bubble" type appearance. Any help would be appreciated.

 

[fishy411]

looks a little like a sponge to me.

 

[duke13]

Looks like sponge to me. Harmless.

 

[dorie]

I have them too, only mine is spreading and taking over a LR.
Also have small green & lavender sponges or carpets? Anyone know what they are, they just started showing up when I upgraded my light system.

 

[dorie]

green sponges or ?

 

[thangbom]

hum.. looks morelike mustard!!!! hey hey what r u thinking??.. he heee j/p

 

[bigarn]

They're sponges.

 

[g-dude]

Dont worry about them... Ive got purple,white,orange and a 3inch patch on my Lr. Just watch it grow because its letting you know that theres plenty of nutrents in your water so thats a good thing