ID please

[sidekicking]

I have no idea what this is
is super tiny. you have to look super close into the tank to be able to see it
about 1/2 big

 

[lilfishie]

Its a feather duster. They are tube worms of a sort that extend what looks like a feather to filter feed. If you put something close to it, it will retract. They come in a lot of different colors, most common are white, brown, red, blue. It may grow bigger.

 

[sidekicking]

that was first guess lol
but I thought it was something else cause I've never seen one that small.
I have another two and they are way bigger than this one
and you can actually see the tube

 

[lilfishie]

These will stay alot smaller than the big tube worms, but it may grow a little. Some like the big ones you have actually build their tube. The little ones like the one you posted a pic of live in the holes in the rock.