Not really a critter, but ID requested

[Ivan75]

Has anyone seen this before? I noticed this as I was feeding today & my Zoas closed up.

 

[Tahoe61]

If you can blow the substance away with a turkey baster or power head then probably poop snail or fish.

 

[ahiggins]

I second detritus

 

[Ivan75]

Awesome. Thank you.

 

[Cary Meredith]

They will eat food you feed other corals as well, I feed my tank every couple of days. They will even eat frozen brine shrimp if you get it right there for them.