How to tell, modern vs fossil shell?

[allmightydoggo]

Hello, how could I tell the difference between a modern shell vs a fossilized shell? I recently found a few shells in the San Joaquin Valley right outside of Gustine. The geological age here is about quaternary. I’ll post a photo from when I found one and to the point I cleaned one. If I can be more specific on where I found it I can, thank you.

[allmightydoggo]

Photos are a little mixed up, sorry.

[Coco]

You are on an international forum and it would be great to specify where this place is.

 

And is it by the sea or by a pond ?

 

Coco

[allmightydoggo]

Garzas creek. There are multiple places on where the creek extends to, but the part of it I went to was mostly just dry and the rest extended to a private property. coordinates are 37.24081° N, 121.07725° W. It’s right near a canal as-well. Most of it was embedded into the ground too.

[Coco]

We need a country, a state, a big city. Do you know where St Barthélemy d'Anjou is ? I do but I’m sure you don’t !

 

Coco

[DPS Ammonite]

Maybe a recent edible clam. 
 

I see now after trying to figure out scale that your clam is probably too be to be clam below:
 

Could it be the fresh water invasive clam

Corbicula fleminea? It lives in western US lakes, rivers and canals. 
 

https://en.m.wikipedia.org/wiki/Corbicula_fluminea

Edited Sunday at 09:48 PM by DPS Ammonite

[allmightydoggo]

I have a few other clams that look like the one I posted. Some are incomplete or either smaller.

[Fin Lover]

26 minutes ago, Coco said:

We need a country, a state, a big city. Do you know where St Barthélemy d'Anjou is ? I do but I’m sure you don’t !

 

Coco

Merced County, California 

[allmightydoggo]

United states, California. Not inside a big city, outside of a small town named Gustine.