Possible early fish gill piece?

[Hat]

Hello. I found this amongst a bunch of Devonian/Mississippian age limestone. Correct me if I'm wrong, but I believe the rock is fossiliferous limestone. These two very odd shapes, one black, one white, I thought could perhaps be the gill structures of something like a Placoderm, Acanthodian, or Ostracoderm.

 

I know it's kind of a tough ID. Any input is appreciated. Thanks.

[ynot]

I can not help with ID, but those are neat looking pieces.

[Hat]

Thank you.

[Al Dente]

The white fossil is part of a brachiopod near the hinge area.

[gavialboy]

thats a unique fossil congrats