Sponge Or Bryozoan?

[Bev]

Ordovician

Prosser member of the Galena Formation

SE MN

Group hunt 8.8.15

I'm thinking that this could possibly be a hindi sponge, but it could just be a bryozoan. What has me is the "pores", they seem to be hexigonal in shape. What do you think???

Thanks for looking!

[Auspex]

I get a bryozoan vibe from this one.

[erose]

Not sure about Hindia but possibly a sponge of some sort although true sponges are apparently rare in the Upper Ordovician.

[Bev]

Yes, sponges are very rare in the Ordovician which is why I got excited!

Bryozoan, in a mound... Praaspora?

[Rockwood]

I think the surface appearance may be deceptive on this one. Look where the interior is exposed. The geometry says coral doesn't it ?

[Ridgehiker]

It is difficult to ID a sponge without looking at the spicules...and difficult to ID a tabulate coral or bryozoan without a cross section. Otherwise we are just comparing images to others found in the area...and those previous may not be properly identified.

None of these three fauna attract much research as they are difficult to diagnose and are not all that useful in Paleozoic biostratigraphy. In contrast researchers tend to use microfossils (conodonts, etc) or rugose corals (as a opposed to tabulate corals)and brachiopods.

My speculation is that it is a bryozoan...just the odds from the age of rock.

When we did field collections and brought back tabulate corals, sponges and Bryozoa they were given a collection locale and then put in trays to taken down to storage drawers in the dungeon. Like Roger Dangerfield they don't get much respect.

Edited August 9, 2015 by Ridgehiker

[Bev]

LOL You are so right, no respect for bryozoa or sponges! Yet they come in fascinating shapes!

Cutting it is not an option at this point.

This is where I really miss Caleb! He knew the fauna of this Ordovician area so well that he could look at it and just know what it was by experience! :-(

[abyssunder]

I see double spiral pattern on the surface. I'm inclined to believe is a bryozoan.

[erose]

The pores are too small for a coral (IMHO) other than maybe Tetradium. As suggested just on it being from that part of the Late Ordovician I would skew toward bryozoan as well. But not Prasopora.

[Herb]

looks like a bryozoan to me also

[Bev]

The pores are too small for a coral (IMHO) other than maybe Tetradium. As suggested just on it being from that part of the Late Ordovician I would skew toward bryozoan as well. But not Prasopora.

Hummm, I'm really stumped now! The only bryozaon it resembles to me is a Prasopora. But then, I'm certainly no expert, it is the one I find so often that humps up like this one. Thanks for the input!

[minnbuckeye]

Hi Bev What does the bottom look like. All of my Prosopora have the distinctive rings. Just gave away 70 prosopora yesterday to children at Fertile Iowa Quarry Days. They were not as impressed with them as compared to the Hormatomas .

Understandable.

Edited August 10, 2015 by minnbuckeye

[Bev]

Hi Bev What does the bottom look like. All of my Prosopora have the distinctive rings

Thanks for weighing in! :-D Can't see the bottom on this one as it is in the rock. I know what you mean about the distinctive rings. It has already gone home with its hunter. :-) I would say Prasopora and a NICE ONE if not a sponge. But I have only found one other Prasopora where the pores are so clear and it doesn't look quite like mine which is why I was going toward sponge - which would be a truly rare find. Even a Prasopora in this wonderful preservation would make me do a happy dance!