Fossil ID, Shape of cup, Kristianstad, Sweden

[Linus]

Hi, I found this fossil at the beach of the lake Ivö-sjön. As far as I know there are two geological periods present with fossils, old and young cretaceous.

The only other fossil I ever seen on the particular location this fossil was found, are ortoceras, or more precisely - probably bellemnellocamax(?)

 

This is quite the big fossil from what you normally would find here. It looks like an underwater plant of some sort?

I wonder what it could be?

 

The complete solid fossil looks like it should be shaped like a glass with a foot. Both the outside and the inside has voids, as if there should have been more material of some sort? even the foot has a very faint outline a bit out.

 

I would be grateful to know what this is.

 

All the best/ Linus

 

 

[Tidgy's Dad]

A sponge, I think. 

Though the inside bit looks more like a bryozoan. 

It's a nice piece, whatever it is! 

[David Konstenius]

Reminds me a bit of the small holes you see in Icthyosaur bones but yeah it's probably a plant of some sort, by the way I'm also from Sweden but have only been there once!

[Tidgy's Dad]

And Belemnocamax is a possibility for the  belemnite. 

Chance of pictures? 

[Rockwood]

6 minutes ago, Tidgy's Dad said:

A sponge, I think. 

Though the inside bit looks more like a bryozoan. 

It's easier to picture the shape functioning as a sponge.

 

[Linus]

Thank you! Sponge/bryozoan seems plausible.

 

18 minutes ago, Tidgy's Dad said:

And Belemnocamax is a possibility for the  belemnite. 

Chance of pictures? 

 

For some reason the belemnite fossils seem to dissolve in the seawater at this site? I found a few 1 km away, but they where in very bad shape. I have no clue why this fossil didn't dissolve?

The lake Ivösjön dropped more than 50cm this summer in the Scandinavian heatwave so the sponge/bryozoan fossil must have been under water for at least several hundred years.