Unidentifiable Fossil

[Mehmet]

My boys and I went fossil hunting in Big Brook New Jersey and can’t identify this one we found. It looks like a worm inside a Belemnite fragment but was told Belemnite fragments are hollow. 

[val horn]

Belemnites are hollow that one w d pointed at rhe other and uften have a.center line.  The piece you shows looks like a broken piece. I would like to see the ends

[Natalie81]

Hi, 

The phragmocone of belemnites are hollow, the rostrum is massive. We need better pictures to confirm if your piece is a belemnite

 

Natalie 

[Rockwood]

10 minutes ago, Natalie81 said:

rostrum is massive

With a radially oriented crystalline structure.

[jnoun11]

its the syphon collapsed when the original fossil was disolved by dame nature and replace by a new mineralisation ,a internal mold with the original syphon.

[Al Dente]

It looks like a boring organism, possibly some type of worm, made a burrow through the rostrum that later filled with sediment.

[TqB]

7 minutes ago, Al Dente said:

It looks like a boring organism, possibly some type of worm, made a burrow through the rostrum that later filled with sediment.

I agree, assuming it's a piece of belemnite (which it does look like). Many belemnites have borings, usually post mortem - this looks a nice one though!

[Rockwood]

28 minutes ago, Al Dente said:

possibly some type of worm

Worms bore ?

[Rockwood]

15 minutes ago, Rockwood said:

Worms bore ?

Yea they do. Siboglinid annelids, bone borers. 

[TqB]

1 hour ago, Rockwood said:

Yea they do. Siboglinid annelids, bone borers. 

Modern Polydora is a very common find in shells and seaside rocks. Being sediment filled, Mehmet's is of course a fossil one. 

 

Modern Polydora in a Megateuthis:

Edited October 17, 2020 by TqB

[Mehmet]

Thanks for the reply. Here is the other side

[Mehmet]

And two more images below. 

[Rockwood]

Looks like it's been split, leaving a half round and exposing the center. A common occurrence for the structure. 

[Mehmet]

So if I am reading everything correctly- everyone thinks it’s a split Belemnite fossil that had a worm bore into it then sediment filled in it fossilizing the worm in the Belemnite fossil? 

[Rockwood]

1 hour ago, Mehmet said:

So if I am reading everything correctly- everyone thinks it’s a split Belemnite fossil that had a worm bore into it then sediment filled in it fossilizing the worm in the Belemnite fossil? 

Although this is possible, it is by no means obvious that the creature which bore into it was preserved. It is only likely that it was a worm. A body fossil would need to be found in the bore hole to confirm it.

[Mehmet]

Ok thanks! 

[Rockwood]

It just occurred to me that we haven't pointed out that the boring is considered an ichnofossil  (trace fossil) in its own right. I can't say the ichno-species but one must be  assignable.