Is this a tooth?

[Silfo]

Hello everyone! I found this one today, and I remember finding another similar  years ago.

 

 

Is this some kind of tooth? in the same place there are a lot of marine fossils, as far as  I know it is not a tooth of shark. Maybe  a cetacean? Not far away I have found a vertebra of a whale.

 

The moment (epic)  when I found it:

 

 

The old one:

 

Salutes from the south, below latitude - 45. Chao!

[Macrophyseter]

Wondering if I could get more views with maybe possibly more clearer pics? 

 

The brown stuff looks like possible enamel to me, but at the same time the "root" is a bit too thin, which kinda makes me uneasy. If it is a tooth, then its not a cetacean either, as their teeth are conical, but this is like flat and sharp on the sides. It really reminds me of a reptile tooth...

[ynot]

I am thinking it is a fin spine from a fish (?)

[Macrophyseter]

My answer from the above post is that I dont really think its actually a tooth, but also, I also think it may be a little too thick for a fin spine either (Unless its coming from a leedsichthys )

[Rockwood]

It may be helpful if you can give us a look at what would be the internal structure. Perhaps an end or one of the cracks.

It sounds strange, but could it be a mold of an entire fin with the spine at the leading edge ?

[Al Dente]

I think it is a bivalve, probably Pinna.

[Fossildude19]

Pinna shell was my first impression, as well.

No enamel, so it isn't a tooth.

[abyssunder]

I'm pretty sure it's a "pen shell" like Pinna.

 

[Silfo]

Hello! busy week =). A few pics.

 

 

Inside structure, it is like dirty quartz.

The  print in the other half