Egg Shells?

[bojo]

Hello,

I have been a rock hunter for a number of years and I run across fossils that are either Crinoids or Bivalves.

I sometimes run across stuff I cannot identify in stream beds and limestone formations while looking for crystals and agates. Over the years I have kept this similar material on the same river but different sandbars over different years in SW Iowa. I thought they were the ball joints of mammals that had been broken by early Americans for marrow. I find no strike marks on the outer edges. (which may have worn off by tumbling in the sandy river bottom). Someone guessed they were turtle egg shells. The strata exposed near find is about 20 feet down on bank which was about 12 feet of top soil and 8 clay. We have a couple of quarries of Pennsylvanian limestone near by. But I think the stuff is 9-10 thousand years ago.

I haven't a clue. The material is about 2.5 to 3 hardness.Perhaps a fossil fan may have run across the like.

I have a number of other material that appear to relate to fossils, and would like to share those at a later time.

[Missourian]

Welcome to the forum.

Those look like phosphatic concretions we find in Pennsylvanian black shale in Kansas City. Here are some from the Muncie Creek Shale:

http://www.thefossilforum.com/index.php/topic/25758-phosphatic-concretions-of-the-pennsylvanian-muncie-creek-shale/page__hl__%2Bmuncie+%2Bcreek

Your first pic could be one split with a fossil in the center. It would be worth collecting more and popping them open to see if any fossils turn up.

[bojo]

Missourian

Sure looks a lot like your samples. Knowledge is a wonderful thing. Thanks for your answer. I am retired to Minnesota now with a whole new set of rock possibilities. Should i find something that looks like an uncommon or interesting fossil, I will pass it along to The Fossil Forum.

If it is not a problem, I have some other things I would like to post that may or may not be fossils. I don't know what I would have done without The Fossil Forum and your time and expertise.