Sponge Fossil?

[Charmin]

We have had a major drought here in Oklahoma and all the creeks are almost completely dry, so we've been walking down the dry creekbeds and checking out places that are usually underwater. My daughter, Josie, found this the other day in a limestone creekbed. It was the only one like it in the creek bed.
It is very porus(I guess that's what you would call it?). And seems to be light weight for a rock this size, it weighs 1lb. 14ozs.
Did sea sponges fossilize?

Thanks for looking and any help!

[Tuberale]

Maybe not a fossil sponge. Perhaps fossilized coral?

[Charmin]

Maybe not a fossil sponge. Perhaps fossilized coral?

Maybe so, Tuberale---Just really eroded fossilized coral? Usually when we find fossilzed coral, you can see each individual cell.....Like this:



Thanks Tuberale!

[Harry Pristis]

Sponges do become fossils . . . rather, sponge skeletons do preserve. Sponge skeletons are spicules of silica, so you can look for patterns of spikey snowflakes under some magnification.

Beyond the spicules, there is typically some pattern evident on the surface. I can't identify in your images any suggestion that this object was part of a living organism. Do you see such a pattern or symmetry?

You may learn more about it by breaking it in two.

[Charmin]

Sponges do become fossils . . . rather, sponge skeletons do preserve. Sponge skeletons are spicules of silica, so you can look for patterns of spikey snowflakes under some magnification.

Beyond the spicules, there is typically some pattern evident on the surface. I can't identify in your images any suggestion that this object was part of a living organism. Do you see such a pattern or symmetry?

You may learn more about it by breaking it in two.

I can't find any "pattern or symmetry" on this thing, Harry. The shape and texture of it just reminded us of a sponge or what we would think a fossilized sponge would look like.
What is the best way to break something like this open? Hammer and chisel? Its very brittle.
Thanks Harry!

[Tigger]

try googling igneous rocks, such as scoria. see if it floats or sinks in water, which should help you narrow it down.
Tigger

[Charmin]

try googling igneous rocks, such as scoria. see if it floats or sinks in water, which should help you narrow it down.
Tigger

Okay, thanks Tigger.

[Solius Symbiosus]

Are there igneous rocks in Ok Well, after a perfunctory search, it appears that the igneous, and meta-igneous rocks in that part of the country are Pre-Cambrian. As such, they would be well indurated and without the pore space that this rock exhibits. Really, too me, it "looks" like a porous flow stone But, I would like to see it under magnification, and "in hand".

But yes, sponges do fossilize, and as Harry mentioned, the spicules/structure can be seen with a little mag.

This is a late Mid-Ordovician chaetid sponge, and a close up, that I pulled from some local rocks.
width of photo about 10cm

Solenopora by solius symbiosus, on Flickr


Solenopra x50 by solius symbiosus, on Flickr

[Solius Symbiosus]

And, here is a large sponge (stromotoporoid) in an outcrop down the street.


Sponge by solius symbiosus, on Flickr

[Harry Pristis]

Good to see you here, 'Solius'! We've missed your knowledge of the Paleozoic.

[RW]

Looks like it could have also been part of an ant bed...