Found these on a beach in the Milwaukee, WI area

[suburbanamateur]

I went to the beach in Doctors Park in Fox Point, WI over the weekend to hopefully find some Silurian reef fossils. Most of the stuff I saw were poor-quality brachiopod fossils, but I these look kind of interesting. 
 

I think the first one might be some kind of a coral, but it does not match any coral fossil descriptions I found on online guides for the area. Yet, it looks more organic the usual porous rocks I on the beaches. 

 

I don’t know what it make of the smaller one: it seems to have more of a pattern than the typical rocks I find that look like a bunch of clams fell into a concrete mixer. But, again, it does not match anything else  in the local guides. 
 

Also, if anyone knows, what kind of rocks typically bear fossils in this area and how to you go about opening them? I’ve only ever used the freeze and thaw method for concretions I found on Mazon Creek, IL, but the stones I find here are completely different. 

 

[Al Dente]

This one is a chain coral. Halysites and Catenipora are possibilities.

 

 

[doushantuo]

a Catenipora as figured in Barrande   

(taxonomy slighty suspect, but the picture is fairly idiotypical, so...) 

Edited March 14 by Kane

[FossilDAWG]

Catenipora has "chains" of corallites that are all the same diameter.  In Halysites there are tiny corallites between the larger ones.  You probably need more "polished" samples to be able to see the difference.

 

Your samples such as the second and third ones are porous rocks, not corals.  They lack any uniformity of structure, or any internal structures such as septa or tabulae.

 

Don

[Fossildude19]

The second item looks like it was bored by something like a wrinkled rock borer.

 

LINK