Gastropod? Speleothem? Rudist?

[Mahnmut]

Hello together,

I just remembered an interesting specimen I have had for many years, my uncle gave it to me when I was a kid. Unfortunately I have no information on its origin. It has some structures that may be diagnostic to the right eye though.

Some pictures of rudists I recently saw reminded me of its general appearance, but now looking at it again I wonder if it is a big gastropod columella. the reddish middle part marked in black is actually standing out much more than the flashlight-picture shows, with cavities left and right that may have connected behind before being covered in calcite. the lower left corner shows some structure, zoomed in on the second pic. there are also some bullet-shaped holes that look like negatives of belemnite rostra or maybe clam borings? (secon pic lower right)

Hoping for your insight,

Best Regards,

J

 

[Myrmica]

The structure on the bottom left of the photo looks a bit like sponge cross sections that I have seen?

[Mahnmut]

Hi again,

as my uncle passed away some years ago and my aunt is going to move to another place, she asked me to look through my uncles collection.

I think I found a piece matching the one he gave to me so long ago. And it is a gastropod, I think?

Best regards,

J

[abyssunder]

The lower left side of your first specimen reminds me of a rudist valve in transverse section.

 

Edited April 28, 2022 by abyssunder

[Mahnmut]

Thanks @abbysunder, Looks like a good fit! Does the gastropod-like spiral form make sense then? I am quite sure the two pieces do at least come from the same place, the collection my uncle left consists of unlabelled subsets of finds from one holiday each +some bought pieces.

best regards,

J

[Mahnmut]

Searched for spiral rudist, may be Caprina? France is a plausible location.

I know in Texas rudists are everywhere, but for me thats a first! Cool!

 

[JohnJ]

@FranzBernhard

[abyssunder]

3 hours ago, Mahnmut said:

Searched for spiral rudist, may be Caprina? France is a plausible location.

I know in Texas rudists are everywhere, but for me thats a first! Cool!

 

 

France might be a reasonable location. Have no better ID than Requenia  ammonia, in this case (for the second specimen).

Edited April 28, 2022 by abyssunder

[FranzBernhard]

Thanks, @JohnJ, but I have no experience with that type of rudists. At least the internal structure does not look like a gastropod. @abyssunder may have nailed it down .

Franz Bernhard

[Mahnmut]

Thanks to all of you,

the rudist hint was what I needed.

Caprina seems like a really good fit: https://en.wikipedia.org/wiki/Caprina

I know my uncle has been to France several times and he would not have brought back these big fossils from a more remote journey by plane.

There is another piece from the garden:

 

[abyssunder]

Just checked the rudists in my collection I found a big one (25cm) resembling yours. It looks that the Caprina adversa will be a good match. R. ammonia is tiny vs. C. adversa and has an operculum (like gastropods).

 

 

 

Edited April 30, 2022 by abyssunder