Very suggestive stone or possible tiny Turtle?

[hndmarshall]

Ok here is another I am not sure of ...I am thinking it needs to go into my "looks like but not pile".... I was told it could be a very small turtle but I am skeptical  so I brought it here for a look and suggestions .... I am thinking it may be just a very suggestive pebble.

 

west of Houston Texas

Brazos River

Gravel bed.

 

[hemipristis]

It looks like it should be something, but I can’t figure out what. I’d definitely have picked that up as well

[Myrmica]

The close-up photo is a little blurry but looks like an eroded flint.  Sorry but unlikely to be a turtle. 

[Randyw]

I gotta go with the interesting rock group.....

[GeschWhat]

I agree with flint/chert. The creamy coating present on portions is usually a giveaway. 

[Plax]

echinoid replaced with chert/flint and then tumbled in a gravel bed?

[digit]

Yup. I'm getting an echinoid vibe from the overall shape as well. Looks like it could be an internal cast that has converted to a nice solid shiny chert. Could also be a chert nodule that has coincidentally been eroded into a very echinoid shape. I'd be more convinced of an echinoid origin if it came from a locality that was known for echinoids of the same general size and shape. Though it looks highly eroded it would be interesting to see if there is any patterning on the surface that might indicate a biological origin.

 

One thing is clear and that is it only bears a fanciful resemblance to a baby turtle. I've seen a lot of baby turtle carapace and plastron bones in a site that preserves turtle specimens well (Montbrook) and none of the baby turtle shells are completely articulated like this nor filled with chert.

 

Cool mystery rock and great skepticism.

 

 

Cheers.

 

-Ken