Unable to identify fossil

[Tschell]

I’ve had this fossil in my collection but never took a deep look at it until now. It seems like it could be a bone or a tooth of some sort. There are calcite crystals that formed on one end while the whole piece has a unique pattern.

[Tschell]

Just figured out it’s a baculite fossil. Also, would anyone know how the patterns form?

 

Edited March 2, 2022 by Tschell

[Mark Kmiecik]

Each row of the pattern is a separate cell of the shell structure. Why this pattern? I don't know, but hang in there, someone else will chime in and perhaps they'll know.

[Ludwigia]

Those are the so-called suture lines which are the impressions of where the walls of the septal chambers attach to the internal side of the shell which show up on the calcitized steinkern (in this case) as these plant-like patterns. Nice piece of Baculite you have there!

[Myrmica]

One idea is that the elaborate, swirly septa gave more strength to the shells, so as to prevent implosion of the chambers that were filled mostly with gas, i.e. because of the pressure of the water outside.

[Ludwigia]

As is proven today in the case of the nautilus. The creatures created their own gas and pumped it into some of the chambers when it wanted to rise up in the water column. There was otherwise enough gas in them for it to remain buoyant. When it wanted to descend, it pumped some gas out. Submarines got this idea from the nautilus, hence the name of Captain Nemo's underwater ship in 20,000 Leagues under the Sea.

[Al Dente]

2 hours ago, Ludwigia said:

As is proven today in the case of the nautilus. The creatures created their own gas and pumped it into some of the chambers when it wanted to rise up in the water column. There was otherwise enough gas in them for it to remain buoyant. When it wanted to descend, it pumped some gas out. Submarines got this idea from the nautilus, hence the name of Captain Nemo's underwater ship in 20,000 Leagues under the Sea.

This description of nautilus changing it’s buoyancy is found everywhere including some peer reviewed papers but unfortunately, it is a myth. Decades ago it was found that modern nautilus maintain near neutral buoyancy and are active swimmers just like other cephalopods. They can remove water from the chambers through osmosis but it is a very slow process. Too slow to use for rising and descending in the water column. Only the chamber next to the living chamber is full of liquid. The other chambers have been emptied.