Help With ID - Possible Coral or Sponge?

[JennLRM]

One of my finds from yesterday. Found it on the surface in a creek bed here in W KY. (That is 99% of my finds!) Apologies for not knowing the geology & time frame. Not quite sure how to go about figuring that out yet. Could this be a sponge or coral? It's about 12 cm long, 9 wide at the widest, & heavy, probably 2 lbs. at least.

[fossil_sea_urchin]

I'm not seeing any features that shout fossil, but I'm not an expert in this topic

[daves64]

Ironstone concretion? Could explain the oxide "rust" on the outside & the weight.

[grandpa]

An interesting rock.  I can see why it caught your eye.  I also believe that it is geological, not fossil.  I think it is some form of cryptocrystaline chalcedony such as chert (flint), jasper or possibly agate.  The last photo, I believe, shows some small quartz crystals a.k.a. druzy quartz.  As to the age of the formation, let me do a little work and get back to you soon.  AND - thanks for the photos.

[JennLRM]

39 minutes ago, daves64 said:

Ironstone concretion? Could explain the oxide "rust" on the outside & the weight.

I did sort of wonder about that. It definitely looks like it has iron in it. Thanks!

[JennLRM]

1 hour ago, fossil_sea_urchin said:

I'm not seeing any features that shout fossil, but I'm not an expert in this topic

Thank you!

[grandpa]

1 hour ago, JennLRM said:

not knowing the geology & time frame. Not quite sure how to go about figuring that out yet.

I think this might be a good basic geological map of Kentucky to start with.  It's fairly general, but much easier to read for a starting place.  Once you find this no longer detailed enough, do a web search on "kentucky geological map" and it will take you to USGS and Kentucky Geological Survey maps that go into more details and are interactive.  But for a good starting point:

 

http://www.uky.edu/KGS/geoky/

[JennLRM]

20 minutes ago, grandpa said:

An interesting rock.  I can see why it caught your eye.  I also believe that it is geological, not fossil.  I think it is some form of cryptocrystaline chalcedony such as chert (flint), jasper or possibly agate.  The last photo, I believe, shows some small quartz crystals a.k.a. druzy quartz.  As to the age of the formation, let me do a little work and get back to you soon.  AND - thanks for the photos.

Wow, thank you so much! It seems to have a bit of everything thrown in there. I have found some iron concretions, some are the smooth purple-red type, (which I see people call Indian Paint Pots), and some are the ones that are blackish and have sort of popped"bubbles", which I see people confuse with meteorites. So this one will be an interesting addition!

[JennLRM]

1 minute ago, grandpa said:

I think this might be a good basic geological map of Kentucky to start with.  It's fairly general, but much easier to read for a starting place.  Once you find this no longer detailed enough, do a web search on "kentucky geological map" and it will take you to USGS and Kentucky Geological Survey maps that go into more details and are interactive.  But for a good starting point:

 

http://www.uky.edu/KGS/geoky/

Thank you! That site is a wealth of info. I can get lost in there like I have in here! I think sometimes I get too much info and my brain forgets the way to sort it.  Appreciate you!