Woodbine/eagle ford border ID needed

[Shaun-DFW Fossils]

I found this in a creek in Tarrant county along the woodbine/eagleford border. Lots of sandstone present in the area, and some concretions. Thanks in advance for the ID assistance!

[DPS Ammonite]

Looks like a concretion. Do the inner and thin outer layers fizz in acid? 

[Shaun-DFW Fossils]

5 minutes ago, DPS Ammonite said:

Looks like a concretion. Do the inner and thin outer layers fizz in acid? 

Thank you! I will have to acquire some acid to try that, I wasn’t prepared..good idea though! What would you do with it next? 

[Lone Hunter]

If you got some vinegar that works too, I'm still with concretion, Eagle Ford has some doozies. Fizz tells you that it's limestone/calcium carbonate. Then you put it on shelf or chunk it

[Shaun-DFW Fossils]

9 hours ago, Lone Hunter said:

If you got some vinegar that works too, I'm still with concretion, Eagle Ford has some doozies. Fizz tells you that it's limestone/calcium carbonate. Then you put it on shelf or chunk it

Thanks! I’ll give vinegar a try. Do you actually soak it to dissolve the outer layer or break part of the exterior with a hammer? This one is so small..lol

[Lone Hunter]

Don't have to break it, you can put the whole thing in and see what it does but sometimes need to scratch it and get some powder then drop vinegar on it. It looks kinda cherty, if it doesn't react at all it's probably chert and not a fossil.