Are these gastroliths?

[ScienceGirl]

Hi! My name is Annika. I have these two stones my cousin gave me. He also doesn't know what they are, but could they be gastroliths? If not, what could they be?

[Tidgy's Dad]

It's impossible to say if they are gastroliths, though a case could be made if they were found in the stomach area of an appropriate reptile, bird or fish especially with others. 

Probably, these are just water-tumbled stones.   

[Thomas.Dodson]

They certainly could be gastroliths. They also might not be. The problem with gastroliths is unless they're found in association with fossil remains then it is impossible to distinguish them from ordinary stones. That said, gastroliths typically show polished high surfaces and the cracks and low areas of the stone usually show little to no polish. The pitting of the one on the left also makes me think water-worn stone as opposed to gastrolith.

[snolly50]

Here is an old discussion thread that may be of interest.

 

 

[ScienceGirl]

18 hours ago, Thomas.Dodson said:

They certainly could be gastroliths. They also might not be. The problem with gastroliths is unless they're found in association with fossil remains then it is impossible to distinguish them from ordinary stones. That said, gastroliths typically show polished high surfaces and the cracks and low areas of the stone usually show little to no polish. The pitting of the one on the left also makes me think water-worn stone as opposed to gastrolith.

Well, the gray one matches the description!!