What are these?

[Rfc100]

Are these three items a petoskey stone, a bone, and a cephalopod? Found in Michigan.

 

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[Perico]

Sorry buddy but not familiar with your area to give you an answer. Hopefully someone has an answer for you.

 

[wherenext1961]

Lower left looks like it could be a Petoskey Stone. Each of the features should be six sided. No knowledge on the others.

 

[GatorBoy]

These are just guesses but they all look like limestone to me.. The top one being just a natural formation or concretion.. Lower left being an impression of a piece of coral and lower right appears to have an impression of some type of plant or coral on it.
Definitely no bone there

 

[yakker]

Horn coral impression (lower left), a rock w/ interesting quartz band through it, or encircling it- with a weird erosion pattern(lower right), and a concretion. My guess. No expert. Yak