Worm or what is this ID

[SHNICI]

Hello all, that's my 1st writing here at R2R.

I got Blue Tuxedo Urchin from LFS, I did conditioning it for about 4-5 hrs to the new tank water. And when I was ready to place the Urchin in the new home, I consider to inspect her properly (for some troubles on it, and I found something black which look like a worm, it's flat, and very fast moving between the Urchin spines. I chase it with super fine tweezers (without touching the Urchin skin, but some spines drop down... ), and too from the worm(the creature) drop down some peaces like scaleс/flakes (they are soft)
Can some one let me know what's the ID of it from the photos?

Regards: SHNICI - Georgi

Top side:

at the bottom side(up side down):

 

[Crabs McJones]

Welcome to R2R!!

#WelcometoR2R
Could it be a fireworm??
Hopefully someone else will chime in

 

[cloak]

Bobbit worm? (or part of one)

 

[SHNICI]

Could it be a fireworm??

I look almost everywhere about but can't find similar one, it don't expand and shrink like them too.

Bobbit worm? (or part of one)

It's not a part of one, it's all together, I watch it under microscope too, I don't see the Bobbits mouth on it, and it's really thin one, I check them too already (fire, bristle, bobbit worms..... I spend over 5 hrs googling around to find something similar to this one, but unfortunately can't....
It's still alive BTW, I drop it in plastic box, full with water and left it in the main tank, to get the same temperature all the time.., it's not that active like when I find it..., but it's still moving under the little rock pieces (hiding), which I put in the box.
If it die, I'll try to take microscope photos on it, just to figure it out (if some one can recognise it..., just to know it was good or bad worm running around on my Urchin shelf.


Regards: SHNICI - Georgi

 

[KJ]

Alitta virens?

 

[SHNICI]

Alitta virens?

Can't find again something from this species to match :S
2 hrs ago I done other shots and I'll post them too, it look like it die (after 4 days in the box, no water flow there, only 3-5 times per day I make water change there 1/2 from the main)
Have to prepare it now for the microscope, because it start to "melt" it self ... (too fast like I see)

 

[Reefer Deez]

I'm Sorry I don't know what it is but I would like to say welcome to R2R

 

[SHNICI]

I found that thread , but there isn't answered too. It now start to look like segmented worm.., but can't be sure and again looking online, can't find similar one.