What is this on my Duncan?

pm_devin · May 14, 2026

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pm_devin · May 14, 2026

Not the hermit crab, the white thing.

ScottJ · May 14, 2026

Maybe @ISpeakForTheSeas might know?

Did you dip it?

commod0re · May 14, 2026

I don’t really know for sure but it kinda looks like another duncan polyp forming to me… pic isn’t super clear so maybe another angle could help?

Euphylliaphyle · May 14, 2026

I think it's a new head forming.

Mebbid · May 14, 2026

I think there's a duncan on your duncan.

pm_devin · May 14, 2026

ScottJ said:
Maybe @ISpeakForTheSeas might know?

Did you dip it?

I did, I used Seachem dip.

Tahoe61 · May 14, 2026

Limpet versus Duncan Bud imo. I suppose Barnacle might be a possibility.

Mr. Mojo Rising · May 15, 2026

A picture with better light will help, it kind of looks like a giant aptaisia to me.

ISpeakForTheSeas · May 15, 2026

Tahoe61 said:
Limpet versus Duncan Bud imo. I suppose Barnacle might be a possibility.

ScottJ said:
Maybe @ISpeakForTheSeas might know?

Did you dip it?

Coral-boring Barnacle - it should shoot out little, feathery appendages to rake in food like fingers closing into a fist:

ISpeakForTheSeas said:
That's a coral-boring barnacle; it's a filter feeder, so it's technically harmless (but large barnacles and small corals sometimes see issues).

ISpeakForTheSeas said:
They're usually not a problem, but they do generally cause a little, dead/deformed patch around where they're burrowed in (and that patch tends to grow as the barnacle does). It being that close to the mouth is a bit concerning to me, but I haven't seen it on enough LPS like this to know if it's an issue.

If you want to get rid of it, I'd imagine you would need to either crush it in its burrow or carefully inject something into it that would kill it - either way, you'd really want to be careful with it being in the coral.