Bioherm? Coquina?

[kerouac22]

Hi all,

Found this in a creek bed, which I think is Mississippian. Anyway, it appears to be a conglomerate of a bunch of tiny crinoid pieces. Little specks come off of it just when I lift it up. I split it in two to see if it went all the way through, which it does (maybe a dumb idea, I later realized).

The only words I can find that come close to describing this are "bioherm" and "coquina," although neither of those really hits it on the head.

Anyway, I'm assuming it's a fossil of some kind?

Thanks for your help.

[jpc]

Its hard to see in the photo, but from your description I would call it a crinoid stem coquina.

[Auspex]

Now that's pretty cool right there! It really is an almost solid mass of small columnals.

[Pumpkinhead]

You could definitely get away with calling that a coquina. Most of the time I hear that term used its with mollusk shells, but the official definition can involve pretty much any invertebrate fragments.

[Auspex]

By definition:

"Coquina (/koʊˈkiːnə/) is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachiopods, or other invertebrates."

[kerouac22]

Thanks, all!