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Goose gastroliths

Anser spp.


Childs marble sized very smooth rounded stones with flats.


Ex- very old well established free-range goose and duck farm.


This area covers many acres and is now a tourist 'retreat' but still has a few free ranging geese. There were probably hundreds of thousands of these stones. Interesting how similar they are when 'finshed with'

No species ID suggestions


Mark Ridgway
Mark Ridgway 4 years ago

Sorry I haven't been able to break one Ava. They're much harder than I thought.

Ava T-B
Ava T-B 6 years ago

They are little treasures. I look forward to seeing the inside, but I'm guessing it's just a piece of quartzite as you say.

Mark Ridgway
Mark Ridgway 6 years ago

@Ava T-B I think you've pretty well got it at least that's how the 'retreat' owner described it.
To quote from Wikipedia bird anatomy...
"Birds possess a ventriculus, or gizzard, composed of four muscular bands that rotate and crush food by shifting the food from one area to the next within the gizzard. The gizzard of some species contains small pieces of grit or stone swallowed by the bird to aid in the grinding process of digestion, serving the function of mammalian or reptilian teeth."
I'm not sure what the original source was for these geese but the resulting stones are very dense and hard - maybe like quartzite (which was available).
I'll try to break one and if it adds to our knowledge I'll report again.

MartinL 6 years ago

You've got to take this one argy...

Ava T-B
Ava T-B 6 years ago

So how does this work? They swallow little rocks for aid in digestion, and over time the rocks all get worn to the same size and shape?

MartinL 6 years ago

You found a category, so it clearly qualifies=)

Mark Ridgway
Mark Ridgway 6 years ago

Hey thanks martin. Couldn't resist putting them here because they are so much 'about' life but are not life in themselves. Makes for an entertaining and enlightening change in here anyway.

MartinL 6 years ago

Well argybee you've got me quite amazed. I don't even know if this is geology, archaeology or biology. If I could think of an award for this one (I'm thinking golf), its yours!

Victoria, Australia

Lat: -37.88, Long: 146.09

Spotted on Jun 3, 2006
Submitted on Jan 3, 2012

Spotted for mission


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