Unusual New Jersey Cretaceous fossil (Wenonah Preservation)

[frankh8147]

Hello everyone! I found this recently in the Cretaceous of Monmouth County, New Jersey by splitting open a Wenonah concretion (which usually contain bivalves, gastropods and ammonites from time to time).

I came across this in one of them and really have no idea what it is. Does anyone happen to know?

-Frank

Edited March 18 by frankh8147

[Tidgy's Dad]

Bit of shell fragment, maybe a bivalve or ammonite? 

[frankh8147]

18 hours ago, Tidgy's Dad said:

Bit of shell fragment, maybe a bivalve or ammonite? 

That was my thought - we just can't find a match. I actually do a lot of work with Wenonah invertabrates but haven't seen a pattern like that.

[ynot]

This is a fracture pattern that is often seen in iron concretions that have a higher iron mineralization, something like hematite or goethite.