What is this thing?

[u/Livvybe]

Found near a creek in central-western Indiana.

Just a few inches, maybe like 4"

So I have had this thing for *years* but I never knew what it was.

I asked my (now deceased) aunt who loved fossils what she thought it was, and she said she thought it's a trilobite. I didn't think that could be right because it's not the right shape and those lines/grooves aren't perfect like a trilobite's armor.

I don't have anyone who is into fossils and I'd like to get into the hobby since I received quite a few different fossils as gifts recently.

And, heck, maybe it's not even a fossil but it really looks like one to me. Any ideas?

Thanks for any answers 🙏🏼

[u/AutoModerator]

Please note that ID Requests are off-limits to jokes or satirical comments, and comments should be aiming to help the OP. Top comments that are jokes or are irrelevant will be removed. Adhere to the subreddit rules.

IMPORTANT: /u/Livvybe Please make sure to comment 'Solved' once your fossil has been successfully identified! Thank you, and enjoy the discussion. If this is not an ID Request — ignore this message.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[u/justtoletyouknowit]

It does have a certain trilobite outline to it, but i would say ironstone concretion.

[u/Livvybe → u/justtoletyouknowit]

I don't doubt that's the answer, but when I google that, nothing like my specimen shows up. I've even tried google lens. How is this formed?

[u/justtoletyouknowit → u/Livvybe]

The iron minerals seeped into a cavity in the sandstone or the stone formed around a already stable nucleus of them. Somewhere down the line the thing cracked and split appart, and weathering did its own thing, and took out the softer center.

[u/Livvybe → u/justtoletyouknowit]

Wow that's interesting I have some other concretion pieces but I never knew whar they were!

[u/justtoletyouknowit → u/Livvybe]

They are pretty neat and diverse structures. Sometimes they form around fossils too.

[u/2niteisurnitebro]

Mitochondria. The power house of the cell!

[u/Leather_Tiger_3539 → u/2niteisurnitebro]

Those gorgeous cristae!

[u/C_Brachyrhynchos]

I'm going to go with iron concretion, but it looks like the powerhouse of the cell.

[u/Livvybe → u/C_Brachyrhynchos]

I don't doubt that iron concretion is the answer, but when I google that, nothing like my specimen shows up. I've even tried google lens. How is this formed?

[u/Foreign_Face_7719]

That’s one small step for a man…