Weird Invert From The Burlington Near Springfield

[Ron E.]

It's the size of a toy top, shaped like one too!

The big cast to the left, i mean.

I've just barely begun breaking open the 200 lbs. of matrix rocks I brought back from last weekend's hunt. Gonna be fun!

[ashcraft]

It may be a monoplacophoran, a group of snail-like organisms whose shell kind of resembled a brachiopod. They were thought to be extinct until a few were dredged up from the ocean a few years back.

Brent Ashcraft

[Xiphactinus]

It may be a monoplacophoran, a group of snail-like organisms whose shell kind of resembled a brachiopod. They were thought to be extinct until a few were dredged up from the ocean a few years back.

Brent Ashcraft

Most of the Missouri monoplacs are in the Cambrian/Ord cherts, not the Mississippian. Most likely, this is a horn coral, or more likely, the base of a crinoid calyx

[Ron E.]

Most of the Missouri monoplacs are in the Cambrian/Ord cherts, not the Mississippian. Most likely, this is a horn coral, or more likely, the base of a crinoid calyx

Here's a more detailed, sharper shot. Xiphactinus, I believe you nailed it with the coral. What a monster! They don't grow 'em that big in the Boone!

And here's a bunch of them on the back side:

This is literally the first rock I broke open. I broke it open in the creekbed where I found it, then scarfed up ten or fifteen more

This is gonna be fun!

[Xiphactinus]

Bustin up Burlington chert is always an adventure! Watch for trilobites!

[Guest N.AL.hunter]

I am guessing a sponge, but really only a guess.