Cap-Gris-Nez: sponge?

[Max-fossils]

Hi all,

 

Found this at the beach in Cap-Gris-Nez, France. The fossils there are usually Jurassic, but I'm not sure if this one is from the same layers. 

Looks like it might be a sponge to me? Maybe not. 

 

Looking forward to your opinions,

 

Max

 

[Max-fossils]

[gigantoraptor]

I don't think this is a fossil, looks more like eroded stone, they can get pretty weird forms sometimes.

[Max-fossils]

1 minute ago, gigantoraptor said:

I don't think this is a fossil, looks more like eroded stone, they can get pretty weird forms sometimes.

That's also a strong possibility. Perhaps one eaten by worm tubes or another lithophagic animal?

[DPS Ammonite]

Looks like it could be a bored piece of sandstone. Detailed up-close photos will show if this is a sponge or just a bored rock. What is the rock made of? If it is all sediment, silt and sand cemented together then it probably not a sponge. If it is a sponge, then you should see organic structures built by the sponge such as pores, canals, spicules etc. Most sponge fossils that I have seen are made of calcite or quartz. 

 

[gigantoraptor]

1 minute ago, Max-fossils said:

That's also a strong possibility. Perhaps one eaten by worm tubes or another lithophagic animal?

I would say worm tubes, but the bigger holes can be caused by bivalves from the genus Barnea. These occur in the North-Sea

 

[Max-fossils]

3 minutes ago, gigantoraptor said:

I would say worm tubes, but the bigger holes can be caused by bivalves from the genus Barnea. These occur in the North-Sea

 

Worm tubes it is. I've collected several Barnea (B. candida) shells, and I am pretty sure that these holes are too small to be made by that species. 

 

5 minutes ago, DPS Ammonite said:

Looks like it could be a bored piece of sandstone. Detailed up-close photos will show if this is a sponge or just a bored rock. What is the rock made of? If it is all sediment, silt and sand cemented together then it probably not a sponge. If it is a sponge, then you should see organic structures built by the sponge such as pores, canals, spicules etc. Most sponge fossils that I have seen are made of calcite or quartz. 

 

I agree it probably is. Not seeing anything that looks organic up close (although I'll check again under the microscope to be sure). 

[Tidgy's Dad]

Pholad borings , in my opinion. 

[Max-fossils]

55 minutes ago, Tidgy's Dad said:

Pholad borings , in my opinion. 

Would be a mighty small pholad then... I think worm tubes is more likely