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Possible pathology or geological process?


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I recently found this bivalve in a Cretaceous deposit. What I find curious is that it has a type of "groove" on one part of the shell.


Three possible explanations come to mind: a possible pathology, a deformation caused by geological processes during fossilization, or the groove was caused by the passage of time and erosion.


This leads me to the following question: how can one distinguish pathologies from deformations caused by the geological processes the specimen underwent?


I'm very curious about this, so I'll be eager to read you!





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Tell me if you need better pics. 

My cellphone camera isn't great:zen:

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Please point out the “groove”. It appears that possible remnants of the original bivalve shell might be present especially in the area on left side of bivalve in photo below. The rest of the area where the shell structure is less evident probably is a very worn steinkern (ST).


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8 minutes ago, DPS Ammonite said:

Please point out the “groove”. 


I apologize, English is not my native language and I didn't find a better way to say what I wanted to represent. Is it like some kind of hole?


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The shell is worn away in the area of the hole and it is caused by erosion of the internal mold of the shell.

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Found this thread; has a lot of great info on this topic:



Here's a few examples that were shared by fellow members in said thread:








All this talk about pathology has reminded me to not quickly discard brachiopods/bivalves when I'm out hunting :)


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