Odd plate with crinoid.

[Icestar]

This one has a decent sized crinoid on one side of the rock, but the other has this weird plate. Is it just a different type of rock within the matrix, or part of something else? Probably Michigan/Indiana.

 

(6/8)

[ynot]

Bryozoan(?).

[Kane]

I'm with ynot on the bryozoan suggestion. The tiny zooecia seem present, and the specimen has that kind of spreading sea-mat appearance.

[Rockwood]

I think it could also be a poorly preserved stromatoporoid, or just calcareous mush though. A closer look at the putative zooecia is needed.