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Some kind of calcified (fossilized?) worm cast


diaseis

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Hi !

So I've found on the beach in french Brittany thousands of those stones (fossiles ? Thingies ?). I started to search the internet to ID them and I stumbled across this website via this post :


So basically they look a lot like wormcast you typically see on a beach but they are solid and look like limestone. I don't know much about fossils so I can't really tell but they definitely feel like limestone and other fossiles I've found before.

Another information that might help with ID is that basically I found them amongst litterally thousands of those but there was no other place were I could find such things anywhere else on the beach. They were in a place with a lot of other seashells, covering an area of maybe 2m² .

I find all of this very intriguing. Do any of you have an idea of what it is ?

Have a good day :)

WhatsApp Image 2021-08-09 at 18.24.34.jpeg WhatsApp Image 2021-08-09 at 18.24.09.jpeg

WhatsApp Image 2021-08-09 at 16.59.49.jpeg

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Hi Diaseis, and welcome to the forum!

 

I think what you have got there is known as "maerl", its a kind of calcified red algae.

Probably not fossil, but a fascinating species anyway.

Best regards,

J

Edited by Mahnmut
correction.
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Thank you so much for this answer !
So I browsed threw maerl images and I think you're completely right. The mystery is almost solved thank you so much !

 

28 minutes ago, Mahnmut said:

Probably not fossil, but a fascinating species anyway.


Well they are truly fascinating indeed and those are amazing creatures. This website Some page about maerls features an image showing exactly what I have found.
 

However there is one thing I'd still be interested to know : according to the very website featuring the following picture,  they say some can be dead and some can be fossilised. Now of course it would be much more romantic if they were fossilized and maybe I'm just biased but they do look like stone. So do you have any idea of how to tell the difference between fossilized maerl and dead maerl (I know both would be dead but yeah) ?maerl_bioimages.jpg

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Hi,

 

Where did you find that ? They are calcareous algae from maerl, but I can't answer to your question...

 

Coco

Edited by Coco
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Well,

as coralline algae calcify while still alive, fossilization would be mainly a question of age. Officially the treshold is 10.000 years, but I personally would be content to call it (sub-)fossil maerl if it was found away from the water. (could be old in the water still). I also think it turns more grey with time, but thats a matter of years at best.

best regards,

J

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Hi ! @Coco I found them on a beach in Golfe de Morbihan (Morbihan Gulf in english if I recall correctly) which is located in Brittany (north-west of France). From what I read, maerl is a species very endemic from Britrany : even the name "maerl" actually comes from here (it's initially "maërl" from breton language, the local language of Brittany.
Apparently it's used as fertiliser and I didn't find a lot of beautiful specimen pictures on the internet (except the picture I reposted on my previous message where they look really beautiful). I don't know if the ones I found are rare but they are definitely gorgeous, at least to me.

@Mahnmut That's really interesting thank you ! Well I'll call them fossils then. If some of the people reading this thread are interested in those, here is a paper about maerl in Brittany which asserts maerl habitats are more than 5500 years old.

Their colour is way more gray than most maerl picture found on the internet.

Well now I want to read everything about it and I'll also go read more about this 10,000 years threshold and subfossil things. Thank you all so much this has been so exciting ! Now I want to go back there and find the most beautiful specimen amongst this wonderful treasure.

Edited by diaseis
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In France, we call fossil everything that comes from an animal or a plant before the appearance of human. After this time, for us it is archaeology and no longer paleontology. So each country has its own standard. In the USA everything that exceeds 10,000 years is fossil. The concept is not the same, it is very confusing at the beginning, but we get used to it.
 
As for the maerl, I found lots of them in Côtes d'Armor (22), the fauna is not fossil at all, I found a lot of current molluscs with beautiful colors. Currently I’m not home, but do not hesitate to reactivate this post in ten days, I still have unsorted maerl, I could make you pictures.
 
Coco
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It's amazing to me how much some of the original pics look like cliona burrow remnants left behind from the dissolution of aragonitic shells. I learned something new today!

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On 8/10/2021 at 10:49 PM, Coco said:
In France, we call fossil everything that comes from an animal or a plant before the appearance of human. After this time, for us it is archaeology and no longer paleontology. So each country has its own standard. In the USA everything that exceeds 10,000 years is fossil. The concept is not the same, it is very confusing at the beginning, but we get used to it.
 
As for the maerl, I found lots of them in Côtes d'Armor (22), the fauna is not fossil at all, I found a lot of current molluscs with beautiful colors. Currently I’m not home, but do not hesitate to reactivate this post in ten days, I still have unsorted maerl, I could make you pictures.
 


Hi !

Thanks a lot for the answer, I guess it's just a question of vocabulary then. I'd like a lot to see your maerl pictures ! I went back on that beach and picked up a lot more (several hundreds actually) of them (maybe I'm obsessed hahaha). Here are some pics taken on the beach. The maerl on the  first picture has quartz cristals in it, I wonder if they were formed via "fossilization" ("stonification"? lol) or if they were incorporated later. Either way, it's shiny and beautiful.


880213244_WhatsAppImage2021-08-11at13_43_43.thumb.jpeg.694703feedd6534410023c8d61b384cb.jpeg

1738064439_WhatsAppImage2021-08-11at14_06_37.thumb.jpeg.e99135cb163f0d8eca49e0150f7b42c2.jpegimage.thumb.png.724c187fe75f023b7503debe4a5c2830.png

Edited by diaseis
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On 8/11/2021 at 4:26 PM, oyo said:

Some red algae from middle Eocene Lutetian South Pyrenean basin.

Perhaps can aid you.

Oooooh those look amazing ! Thanks so much ! I'm now pretty sure what I found is quite" recent" maerl (not called "fossils" by french as @Coco said) but the ones you showed have a lot of similarities it's intriguing. I was actually planning to do some trip with my girlfriend (we're both into fossils and geology even though we both don't know much about it) to the Pyrenees to see some geological curiosities and randomly pick up fossils. Hope we stumble across such amazing ones (doubt that though but still).

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I just came back a few days ago. I’ll try to get you some pictures by the end of the week.
 
Coco
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Hi,

 

@diaseis here some pics about maerl.

 

Natural maerl, unwashed, not sifted

1-Maerl-brut.thumb.jpg.14fc8771f0bca927cc02dfb3e962f32f.jpg

 

Calcareous algae

2-Algues-calcaires.thumb.jpg.748a31f41c9acce8bcdad49534a4770b.jpg

 

 

Some species of gastropods living in the maerl (Calliostoma zizyphinun, Gibbus magus, and various small species)

3-Calliostoma-zizyphinum.thumb.jpg.d3d96286f44bedbb4f414c0baad502a2.jpg

 

4-Gibbula-magus.thumb.jpg.6068393b5f250901c349d357c95bdff6.jpg

 

5-Divers-gasteropodes.thumb.jpg.aa046d552371282068caa9bb64bed799.jpg

 

If you have some shells from your spot, please post them ;)

 

Coco

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@Coco Wooow your collection is awesome ! I was actually considering buying a lot of boxes to do some sorting. I found a couple of nice seashells there indeed but I didn't keep a lot of them. I've been reading a few posts of yours you have linked in your signature, I utterly love how passionate and how much you know about all of this. I'm currently ultra motivated with fossils (I had a specific interest about it when I was a kid from about 8 yo to 12 yo before it shifted to music and now I feel like it's coming alive again, I feel this post and the maerl had a part into this).
With my girlfriend we collected some nice fossils in the wall next to my house, I wonder if I should talk about this here, I guess they have nothing special, would you guys want to hear about it ? I don't really know this community, sorry if I'm inappropriate.

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Hi,

 

Thanks for the compliments, but being passionate at this point also causes disadvantages !

Anything that talks about fossil has its place here, creates a new post with your fossils, and if you need help identifying them, there will always be someone here to guide you at the very least.

What region are you in ? France is vast and it’s not very precise in your profile ! ;)
 
Coco
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On 8/23/2021 at 9:13 AM, Coco said:
Thanks for the compliments, but being passionate at this point also causes disadvantages !

What region are you in ? France is vast and it’s not very precise in your profile ! ;)

I live in Vincennes, a suburb of Paris, I'm gonna precise it on my profile (precision is key I totally agree).
Well I think I can relate on the disadvantages of being passionate about something to some extent (mainly category theory back when I was basically only doing math in my life). Your collection must be awesome (and must take a lot of room hahaha)

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