Eocene - Pleistocene Ichnofossil from Venezuela

[GeschWhat]

Here is one that has me stumped. It was purchased as a possible coprolite. However, unless the critter ate a lot of dirt, I'm thinking it is some sort of steinkern. It has a smooth texture on the outside (like it was coating in a thin layer of iron-rich silt, but is very gritty on the inside. It was found near turtle remains. I will post a microscopic image in the next window.

I have come across similar configurations (on a much smaller scale) in the Rattlesnake Creek micro matrix, but I don't know what those are either. I apologize in advance for the quality of this photo. I would happily retake it at a better resolution if anyone thinks it would help.

Thanks for looking!

Edited March 2, 2016 by GeschWhat

[GeschWhat]

Here is a magnified view of one of the chipped areas. All the areas where the interior composition is exposed are pretty much the same.

[Auspex]

My impression is that it is a carbonate accretion.

[GeschWhat]

Thanks, Auspex. I've never heard that term before...so much to learn! I googled for images, and it does look like that. Most of what I found talks about man-made accretions used for coral reefs. Do you know, does it initially start up around dead corals? Just curious as to how it gets it's shape. Do you think the micro specimens from the Rattlesnake Creek matrix are the same thing or are they internal molds of some sort. Those (Rattlesnake Creek) have the same composition as a lot of the bivalve and gastropod steinkerns I found in the matrix. I know so little about ocean formations.