Sponge? Stromatoporoid?

[DANR11]

I found this fossil near Rockford, IL in a creek bed. The native bedrock here is Ordovician, however I am pretty sure most of the rocks in this creek traveled here on a glacier. It's fossilized in sandstone, which I think is pretty cool, but I'm not sure what it is. A sponge? Stromatoporoid?

[ashcraft]

I think it is a coral, chain coral maybe? Somebody else will know, don't know alot about corals.

Brent Ashcraft

[Missourian]

It could be a bryozoan.

I've found weathered Fistulipora with a grainy texture like that.

[Indy]

I think it is a coral, chain coral maybe? Somebody else will know,

don't know alot about corals.

Brent Ashcraft

I don't see Chain Coral...

Below is a picture of a "Chain Coral"

Edited December 29, 2011 by Indy

[squalicorax]

could be Tetradium

[DANR11]

I agree it's probably not a chain coral. I'm still thinking stromatoporoid, I've seen some with a very similar layered appearance.

[Rockwood]

My vote is a fine grained tabulate coral. I'm not sure the terminology is correct. An incrusting type with small polyps is what I'm referring to.

[Indy]

Not focusing on the layering structure...

I see features on the surface pointing to

Sponge, Bryozoan, or possibly Coral

You have the fossil in hand...and can best see

the structure in this area on the fossil

What do you see ?

[Plax]

gross morphology looks like a broken off section of Hydnoceras but not sure that genus of sponge is ordovician

[igneous_is_bliss]

My vote, if it counts, is Stromatoporoid. See this link, maybe you'll find it useful: http://soliussymbiosus.wordpress.com/2010/06/03/sponges/

[araucaria1959]

I'm not sure, but I think stromatoporoid, too. It looks also like the tabulate Alveolites, but as far as I know Alveolites doesn't occur as early as ordovician. It could help to polish a part of the fossil to see details of its structure. I know about the problem to distinguish between stromatoporoids and certain tabulate corals (especially Alveolites) from middle devonian reefs here in Germany (Eifel region, also famous for its trilobites).

araucaria1959

[Rockwood]

My vote, if it counts, is Stromatoporoid. See this link, maybe you'll find it useful: http://soliussymbios.../06/03/sponges/

Your participation counts, but all are free to tally the votes as they see it.

[DANR11]

Not focusing on the layering structure...

I see features on the surface pointing to

Sponge, Bryozoan, or possibly Coral

You have the fossil in hand...and can best see

the structure in this area on the fossil

What do you see ?

Looking closely I can see the resemblance to a bryozoan in terms of surface features, however the grain size makes it difficult to decifer any definitive details. I suppose it shall remain a mystery. Looking on the bright side, I've learned a bit more about sponges and stromatoporoids in searching for an answer.

[DANR11]

gross morphology looks like a broken off section of Hydnoceras but not sure that genus of sponge is ordovician

Being part of a glacial deposit, I suppose it could have come from Cambrian or Silurian deposits further north in Wisconsin.

[Indy]

We are looking at pictures and rendering our opinions and often our best guess.

Just because a positive ID is not rendered here does NOT mean specimens can

not be identified...Not all rocks and fossils can be positively identified based on pictures

If you really want to press for an identification...Take the specimen to a local authority

to be examined in person. Close examination by an authority will often result in an

identification.

[Rockwood]

We are looking at pictures and rendering our opinions and often our best guess.

Just because a positive ID is not rendered here does NOT mean specimens can

not be identified...Not all rocks and fossils can be positively identified based on pictures

If you really want to press for an identification...Take the specimen to a local authority

to be examined in person. Close examination by an authority will often result in an

identification.

Amen

[DANR11]

We are looking at pictures and rendering our opinions and often our best guess.

Just because a positive ID is not rendered here does NOT mean specimens can

not be identified...Not all rocks and fossils can be positively identified based on pictures

If you really want to press for an identification...Take the specimen to a local authority

to be examined in person. Close examination by an authority will often result in an

identification.

Well said. I posted it in the hopes there was some critical characteristic I was overlooking that someone else might catch. I might take it to a local museum and hopefully get connected with someone who really knows this area. Thanks.

[ghost1066]

Well said. I posted it in the hopes there was some critical characteristic I was overlooking that someone else might catch. I might take it to a local museum and hopefully get connected with someone who really knows this area. Thanks.

I usually call our state geology dept. I can send them an email and I have always gotten an ID. If they don't know it they send it around until they get one then get in touch with me to let me know what I have.