Is the a tiny feather duster?

[zerozero]

Saw this today behind a rock (so can't get a better angle of it). It disappears/retracts when I cleaned the glass to get a better look at it. Only to come out again after a few seconds. Also retracted when it sensed me looming. All the filaments/arms appear the same length and make a perfect little bowl. It's less than half a cm across.

Any ideas anyone?

Kill or keep?

 

[IKD]

Looks like it. Harmless filter feeder

 

[zerozero]

Thank you! That's pretty cool. I'm all for some benign biodiversity.

 

[Court_Appointed_Hypeman]

It might just be an artifact in the picture from movement, but it doesn't look quite the right texture to be a feather duster, the shape it's at, unless there is a lot of flow on it doesn't look quite the same either