Bivalve? Brachiopod? Other?

[butchndad]

What are these and please don’t say they’re concertina

[Jeffrey P]

Most or all of those appear to be arm segments and partial claws of Protocallianassa morton, a ghost shrimp. Those are fairly common in the Cretaceous streams of New Jersey.  

[Plax]

Those crabby concretions also provide some other rare species so keep looking at these by all means. Some of the parts in your pics may be from Hoploparia but Jeffrey is most likely correct.

[FossilDAWG]

Just because I know everyone loves making new labels, the current name for this ghost crab is Mesostylus mortoni. 

Maybe you could post a photo or two showing the larger specimen on the right from some different angles?  Also the claw bit on the middle left?  They might be something different, such as Hoploparia, but I'm not certain of that.

 

Don