About a centimeter? What is it?

[bristleworm]

It's blue gray, asymmetrical and slowly moves across the rock work. About 1 centimeters across.

 

[nautical_nathaniel]

Really hard to tell. See if you can catch it somehow and place it in a white bowl with a bit of seawater, then take a pic out of the blue lighting.

 

[bristleworm]

Little better pict

 

[bristleworm]

I can easily get at it with a forceps but if it's beneficial I'm worried I would harm it by pinching it.

 

[bristleworm]

Just to add, it has a rough surface like a starfish

 

[JTP424]

My guess is a piece of Asterina Starfish.

 

[bristleworm]

Friend or foe?

 

[bristleworm]

My guess is a piece of Asterina Starfish.

You nailed it. Did a little research and pulled it. Seems they get mixed reviews, so it got yanked.