Small and large lobster?

[mateosfossils]

This is from a basement construction project in southwest corner of Wisconsin. We literally dug out a hundreds of thousands of fossils, 4' underground. They were in a 3-8" thick layer of concrete along with a type of brown sand/dirt full of other fossil parts. Out of the 6 hills of earth approx 12' high each, only the first hill is dirt. The other 5 are nothing but fossil's!  I'm completely green to the fossil world so I'm doing my best here lol. In this particular rock I noticed several small 1" lobster things. Then I noticed what looked like bigger legs. One leg goes through a hole and out the other side (pretty cool)

Ask me anything else and I'll answer as well as I'm able. Thanks. I'm sure I'll have endless questions as we pick through this rubble.

[Kane]

The first cluster of images look to me like in-filled burrows (ichnofossils). In the closeup images, I think I see some bits of crinoid and other related marine fossil fragments. 

[Mark Kmiecik]

I see crinoids, bryozoans, bivalves and possibly burrows. Google if you don't know how some of these look.