Weird find

[VB313]

I know this is gona sound wierd I can’t even believe it but tonight

noticed a crater in my sandbed that was not there earlier in the center found this brown looking egg/clamshell I pulled it out of the tank and could see it was split like a clamshell I opened it and inside was what looked to be a small bristle worm I poked it with a pen tip and in the dark the worm like things lit up green line glow in the dark green lightning bug stuff where it was poked I couldn’t believe it and showed my gf and she confirmed it glowed when poked what is this? Inside shell thing:

I know the pics aren’t great best I can do at the moment

 

[Ranjib]

Hard to say, can be bivalve or chiton. Do you have a photo of when it was attached to the rock?

 

[VB313]

Hard to say, can be bivalve or chiton. Do you have a photo of when it was attached to the rock?

No I don’t I wasn’t concerned when I first seen it just figured it was a common bristle worm hiding but when I poked it I couldn’t believe the glowing

 

[Ranjib]

can be isopod.. i dont know :-/

 

[Softhammer]

The shell is a pen shell. A small one and I’m sure the worm was using it as a hideout. Those shells are a very common find in live rock holes. Almost alway dead too.