Late Ordovician stellate ossicles

[pefty]

We've been finding these oddball puffy stars in the Late Ordovician (Sandbian) of eastern Missouri (Illinois Basin), in the uppermost part of the Plattin Group (a Platteville equivalent) or possibly the lowermost part of the Decorah Group (Katian). We've been finding a lot of weird fossils in that zone, including articulated cyclocystoids, but these I'm at a loss on. They seem to be calcite and preserve in the same texture and color as other echinoderm material in the same rock. They vary in convexity and in the presence of a central hump or divot, but there never seems to be a lumen that goes all the way through as far as I can tell. Some possibilities: 

• stelleroid
• crinoid (but where anatomically?
• cystoid (but where anatomically?

Up for other ideas or insights. Seen anything like this before?

              

[connorp]

Maybe starfish ossicles?

https://equatorialminnesota.blogspot.com/2019/08/platteville-sea-stars-and-cystoids.html

[pefty]

10 minutes ago, connorp said:

Maybe starfish ossicles?

 

https://equatorialminnesota.blogspot.com/2019/08/platteville-sea-stars-and-cystoids.html

 

Ah brilliant! Makes total sense agewise, same set of rocks. Many thanks!

[TqB]

Starfish ossicles seems a good possibility, more so with other sizes and shapes scattered around like upper centre and lower right here.

Size may be an issue though, with larger ones seeming to be about 4mm across?

EDIT: I think the rectangular one at the top is broken so it's probably the same as the others.

 

Edited March 10, 2021 by TqB