Oddball Mississippian bryozoan we think

[pefty]

Identification help requested! In presumable Burlington chert (Mississippian: Tournaisian/Osagean) of east-central Missouri (Lincoln County), USA, I recently came across a mostly moldic chert specimen of what must be a bryozoan, but I do not know what early Mississippian bryozoan would possess such a robust axis devoid of zoœcia, as in the later Mississippian Lyropora. At first I was not even sure it was the bryozoan’s own axis but instead thought the bryozoan was somehow associated with an orthoconic cephalopod. Each photo below is paired with its optical inversion to help visualize what originally filled the mold. Scales in mm. 
 

 

 

The main reason I feel confident that this whole structure is bryozoan is thanks to a colleague’s find of a presumably related unidentified bryozoan, also in moldic chert presumably from the Burlington Formation but from southwest Missouri, that shows the axis and its texture much more clearly than mine. Here is that specimen, again with inversions. Again I have no knowledge of an early Mississippian bryozoan built like this. 

(Yes, the axis surface texture looks quite a bit like the texture along the genal rim of some Mississippian trilobites! But it also resembles undoubted bryozoan textures I’ve seen.)

Identification help requested!

Thanks.