Can anyone tell me what this egg like rock is?

[BunnySue]

I found this rock several years ago in SW Ohio and cracked it with a hammer. I'm not sure why I did that but was surprised with the results. It is very smooth on the outside and has a gritty inner rock inside. I'd appreciate any info anyone has to share. I know nothing about rocks except that I like them. Thanks for looking!

 

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[Rockhunter1620]

Old river rock, sedimentary, sandstone w/outer layer of hardened clay? I'm guessin.

RH

 

[BunnySue]

Thank you so much! I plucked this from the wall of my basement before the walls were poured during construction. I live within a mile or so from the Miami River and near many gravel pits so that makes a lot of sense. My friends have some pretty impressive arrowhead collections from the area that have sparked some interest in poking around the ground. This is one of my favorite finds so far.