Sponge or Bone ?

[Yannickrb]

Hello! 
 

its my first time writing in this forum. 
i am from Germany and usuals discuss my findings in a German forum. But this time no one was able to identify my new fossil.

 

it was found at the cost of the Baltic Sea in northern Germany. (You can expect fossils from every age, because of the ice age) 

 

You can see a sponge like structure with some big channels.

It seems that the sponge like structure was once covered from some kind of “skin” as you can see in the pictures. 
the fossil measures 10“ x 4,7“ (25cm x 11cm) and seems to be heavy as a normal rock.
 

in a German forum it was discussed if it could be some part of a big bone or rather some kind of sponge. 
 

hopefully some one of you does know the answer. 
 

please excuse my bad English and have a nice day!

 

yannick

[Rockwood]

 This one almost makes me wish sponges had bones. 

I don't really think it's either, though. 

[TqB]

I think it might be a silicified and weathered heliolitid tabulate coral. (Look up "Heliolites" for better images than "heliolitid"!.)

Edited March 8, 2022 by TqB

[Wrangellian]

My first thought was sponge - it looks a lot like ones found in Arizona, in preservation style at least.  @DPS Ammonite

[DPS Ammonite]

I have seen nothing like this in Arizona. I looks like coral more than a sponge. 

 

 

[Yannickrb]

Thank your for your help! 
I found some pictures of Heliolites Corals that come very close. Sadly I found no picture that matches the structure of the pores and channels 100%, but i have red some descriptions of species with no pictures available such as the Heliolites Spongodes. That one sounds very promising to me. 
 

In conclusion I’m pretty sure it’s some kind of (for my region) unusual coral.

Edited March 9, 2022 by Yannickrb

[FossilDAWG]

I also think it is a heliolitid coral.  It looks as if it might be silicified, which can distort the features somewhat, making some structures thicker than they otherwise would be due to recrystallization, and emphasizing others due to differential silicification and erosion.  In such a case, it might be difficult to compare directly to non-silicified specimens of the same species.

 

Don