Late Ordovician segmented.......thingy.

[pefty]

A friend uncovered this oddball today in the Late Ordovician (Sandbian) of eastern Missouri, in the uppermost part of the Plattin Group (a Platteville equivalent) or possibly the lowermost part of the Decorah Group. He's been finding a lot of weird fossils in that zone, including articulated cyclocystoids, but this one I'm at a loss on. Too wobbly for an orthoconic cephalopod, too much space between calcite elements for a crinoid column. Given the size, is machaeridian a possibility? What other ideas should we be considering?

Edited November 17, 2020 by pefty
clarify meaning

[Rockwood]

2 hours ago, pefty said:

too much space between calcite elements for a crinoid column.

Looks pretty normal to me.

[FossilDAWG]

My first impression is that it is a siphuncle of an actinocerid nautiloid.  The "waviness" may be because specimen is at an angle to the matrix surface, and the matrix surface is not flat so the specimen is more exposed or more buried from place to place.  The fossil may be at least partly silicified so it tends to stand out from the matrix.

 

Don

[Rockwood]

Wow ! Now that it's pointed out I don't believe I didn't see that. 

[pefty]

Thanks, you two, for the helpful discussion. I came across a photo of a similar specimen of a cephalopod:

 

 

So....cephalopod it is

[LabRatKing]

And here I have been tossing similar finds aside thinking " ...another %$$#^ columnal..."