Some kind of belemnite?

[Metopolychas]

I'm guessing it's a squid of some kind, but I didn't think they split diagonally? 

 

Pictures to come. 

[Metopolychas]

[Metopolychas]

[Metopolychas]

This part split in two. 

Another part also show lines in the 'shell' but was hard to get a picture of. 

[Metopolychas]

You kinda see the core (?) but all the bits had that 'roof' over them, and on the biggest piece there were sort of ribs on the roof. 

[Metopolychas]

Found in what's supposed to be silurian deposits (but could easily be older or younger, not very detailed map). The whole piece is about 10 cm long and the biggest part of the core is 3 cm while the 'roof' is 6 cm. 

[Ludwigia]

Belemnites only occur in the Mesozoic, so this is probably part of a straight nautiloid.

[Metopolychas]

Not the best pic but it has a core within the core. 

[Metopolychas]

Thanks, ludwigia! Leaving something new each time! Do you think that roof with the ribs is part of the fossil or just a coincidental formation in the rock? 

[Fossildude19]

If not orthocone nautiloid, my next guess would be infilled burrow of some sort. 

With the concentric layers, it could also be a concretion. 

I cannot tell, as I don't see any evidence of a narrowing of the item, like with orthocones.

 

[Metopolychas]

It does narrow, from 3 cm on the big piece to about 1.5 cm on the last pic with the black circle. There's also the diagonal disks that split (pic 3).

 

I'll be trying to prep it a bit to get a better picture.