mollusc or sponge

[Gen. et sp. indet.]

Campanian, southern Poland, strata rich in sponges and echinoids

 

[Al Dente]

It might be the sediment that filled a vase shaped sponge.

[Gen. et sp. indet.]

Thanks!

Others agree?

[M Harvey]

Looks mollusk to me.  I'm seeing concentric growth rings.  The symmetry similar to a limpet. 

[Paololitico1972]

I have this specimen very similar..

For me, a sponge ;-)

 

(also see here: http://www.paleomania.com/album-309929.html )

[Guguita2104]

Nice find!

I would go with vase shaped sponge,as well...But I'm not totally sure

 

[Gen. et sp. indet.]

Thanks all