Various big bivalve shells, oysters, perhaps some other stuff

[Brad1978]

Thank you very much.  The Dry Frio River bed has alot of ancient artifacts from the Cretacious Lower Gulf and the Upper Gulf.  Lots of them haven't been discovered yet.  The fossilized oysters are pretty common on the Frio.  I've seen several of them.

[abyssunder]

It's not clearly visible in the picture in question how the scars are arranged, but  not all of them are arranged in a regular manner, so I think we are dealing with an non-echinoid hard substrate, an attachment to a barnacle colony. I wish I could have better photos to make my theory sustainable.

 

my specimen - oyster lower valve attached to a barnacle colony (cut)

[pambosk]

Thanks for all the replies, friends, I also believe now that those are tracks from where the oyster was hanging from, while growing up.  

 

Just so I get my areas straight can anyone tell me if such a fossil and all of the above fossils actually can be considered Miocene?

[pambosk]

On 9/19/2017 at 3:09 AM, abyssunder said:

It's not clearly visible in the picture in question how the scars are arranged, but  not all of them are arranged in a regular manner, so I think we are dealing with an non-echinoid hard substrate, an attachment to a barnacle colony. I wish I could have better photos to make my theory sustainable.

 

my specimen - oyster lower valve attached to a barnacle colony (cut)

 

Ok i ll try and descibe the marks: it is 3 parallel rows of perfect circles, 4 circles on each row, on the 1st row, the two first marks look more like dots than circles.

 

vertically there is a row of 6 small rectangular/linear markings in perfect alignment to each other.

 

so imagine 12 balls moving in 3 parallel lines and being blocked by 6 perfectly aligned same sized poles.   I hope this helps a bit

 

also i just took a pic, i hope it helps also 

[pambosk]

 

The photo below of a Oligopygus haldermani

It matches he pattern.  I thing our oyster grew up on an urchin skeleton?