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Help with identification. Found in San Antonio


Breezy2428

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It may be a natural cast of a crustacean burrow. Thalassinoides is the term used for such fossils. The burrows are sometimes thought to be created by crabs. 

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Although the overall form looks like 'something', it is just eroded limestone full of small marine fossils. 

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The human mind has the ability to believe anything is true.  -  JJ

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46 minutes ago, JohnJ said:

Although the overall form looks like 'something', it is just eroded limestone full of small marine fossils. 

The soil in my yard is full of such shapes, but the creek next to it is full of burrow casts. How have you so completely ruled out the possibility? 

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The San Antonio area karstic rocks and aquifers account for large amounts 'holey' rocks.  Freeze/thaw fractures, ancient fires, and other factors break the larger rocks into smaller unusual shapes that are further eroded by the chemistry of rain and soil.  As a result, strangely shaped rocks are common in the general area.

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The human mind has the ability to believe anything is true.  -  JJ

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  • 2 weeks later...


I found something similar near San Antonio with the same coloration and texture.   About 7 inches long and hard (doesn’t scratch with a nail).  Groove on one side as seen in pic. A couple 1/2 inch fractures on one end that make me think it’s or organic origin and may be a bone cast.  Any thoughts?

 

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1 hour ago, FireAway said:

I found something similar near San Antonio with the same coloration and texture.   About 7 inches long and hard (doesn’t scratch with a nail).  Groove on one side as seen in pic. A couple 1/2 inch fractures on one end that make me think it’s or organic origin and may be a bone cast.  Any thoughts?

Rock has no bone texture.

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10 hours ago, FireAway said:


I found something similar near San Antonio with the same coloration and texture.   About 7 inches long and hard (doesn’t scratch with a nail).  Groove on one side as seen in pic. A couple 1/2 inch fractures on one end that make me think it’s or organic origin and may be a bone cast.  Any thoughts?

 

IMG_1409.jpeg

IMG_1521.jpeg

That looks like caliche https://geokansas.ku.edu/caliche#:~:text=Caliche is a broad term,beds that stretch for miles.


I got familiar with it while in grad school at UTEP.  

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16 hours ago, Baking Geologist said:

That looks like caliche https://geokansas.ku.edu/caliche#:~:text=Caliche is a broad term,beds that stretch for miles.


I got familiar with it while in grad school at UTEP.  

 

I've heard it referred to as calcrete.

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Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

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