What is It and Should I Worry?

[AKL1950]

Can’t remember if I ask about this before, but trying to understand what it is and whether it presents a problem to the tank.

it appears to be some sort of filter feeding orangish web that is restricted to the underside of the rockwork where the light doesn’t hit it. Pretty sure it’s not algae or cyano, but maybe a sponge network. Really, the only time you can see it is when you hit it with a white light. The only time I’ve seen it on corals, it‘s corals that are dead or dying from probably other issues and it starts covering them on their dark side away from the light.

To get it to show, I’m using a bright white led flashlight. There are some filter feeding small sponges in it, but I’m not sure it’s they are part of it or separate organisms. Any ideas?

 

[dwest]

Sponge. No worries.

 

[ISpeakForTheSeas]

Looks like it's probably a sponge network to me - as long as it doesn't start growing over and smothering corals, it's probably harmless/beneficial.

 

[OrchidMiss]

Certainly looks like sponge to me. I have something very similar, if not the same, in my 55g.

 

[AKL1950]

Okay, sounds good. This is an Acro that has it all over it, but I think this Acro was already dying before it got covered. Lostvanother Acro in that same area to the right of it. I’m assuming they were too low in the tank and not getting enough light, but since both of them were covered with the stuff, I wasn’t sure.