Is this a fossil?

[mamaniece]

I found this on a beach in Ventura California.  I immediately wondered if it might be a fossil.  I recently visited a museum in Wyoming that has similar item on display. 

[DPS Ammonite]

It looks like some recent clams that burrowed into some relatively soft Monterey Formation rocks.

[Coco]

Hi,

 

They are pholads, marine bivalves that dig in the rocks or in the floating woods. They seem to me recent.

 

Coco

[Shellseeker]

I have often seen the holes in Dugong ribs and Meg roots (both fossils from the Miocene). The Peace River dissolves or transforms calcium carbonate. I think I have never seen any residual pieces of shell materials in those holes. 

My curiosity forces me to ask about the process.  

Is it likely that the Ribs/Roots were NOT yet fossilized when the holes were drilled ?

As Coco indicates this may be "recent".  How long is the process of dissolving shell materials versus the process of fossilization in it's host?

 

As my hunting part frequently tells me on a different process,  Almost all the broken Megs we find were broken before fossilization,  not by the River or by my shovel.

[Carl]

7 hours ago, Shellseeker said:

I have often seen the holes in Dugong ribs and Meg roots (both fossils from the Miocene). The Peace River dissolves or transforms calcium carbonate. I think I have never seen any residual pieces of shell materials in those holes. 

My curiosity forces me to ask about the process.  

Is it likely that the Ribs/Roots were NOT yet fossilized when the holes were drilled ?

As Coco indicates this may be "recent".  How long is the process of dissolving shell materials versus the process of fossilization in it's host?

 

As my hunting part frequently tells me on a different process,  Almost all the broken Megs we find were broken before fossilization,  not by the River or by my shovel.

I have seen examples in the Pliocene of California where modern pholads clearly bored into fossil bones. But they were also present in the Pliocene there so I suspect that they were doing this for the last 6 million years there and that context would be critical in determining if the borings were modern or fossil.

Edited October 2 by Carl

[ezeemonee]

Ventura County and next door Santa Barbara County do have some good spot for marine fossils from various eras but these are probably modern.  Nice find though!