what is this under my montipora?

[LeoB]

my montipora has been bleaching and this weird white thing has been getting bigger under it (see pic around the plug); what is it and do you think it's the cause of bleaching? the edge of montipora that's away from the plug is still growing great and the rest of the corals doing fine. should i scrape off the white lacy thing and dip it or simply discard this piece?

[WV Reefer]

8 minutes ago, LeoB said:

my montipora has been bleaching and this weird white thing has been getting bigger under it (see pic around the plug); what is it and do you think it's the cause of bleaching? the edge of montipora that's away from the plug is still growing great and the rest of the corals doing fine. should i scrape off the white lacy thing and dip it or simply discard this piece?

it is a sponge and some of them can grow quite quickly.  I would just try to remove it outside of the tank.

[A Little Blue]

I like sponges. One day you gonna wish you had more. Great filter feeders and extremely beneficial to established aquarium. 

[banasophia]

Yes agree with others white lacey thing looks like sponge, plus something else on the other side that’s even brighter white makes me think of the nudibranch I just found on the underside of my Fiji yellow. 

[12scanlon]

I have sponges like those on my snails shells. Very cool 😎.

[KNelson]

I have a sponge that is starting to grow onto a ric, it's 'yuge.  Might have to get rid of it, but there are a few more like that and hundreds of pineapple sponges top take up the slack.   The brighter white thing is a feather duster with a red fan.