We Found Some Fossils In Our Northern Illinois Backyard - November 2021

I was out in the backyard doing what I spend most of my free time doing these days:  dealing with the leaves.  We have a mix of native trees (Kentucky Coffee Trees, Hackberry) and a couple of large Oak trees.  The Oak leaves come down differently than the the rest of the trees.  Rather than dropping them mostly at once, our Oaks drop leaves a little bit at a time.  And the Oaks are HUGE, so there are TONS of leaves. That means, Oak leaf cleanup lasts for weeks.  

How I start my cleanup is by blowing the leaves into the lawn where I collect them in big piles then I begin to mulch them in and bag some of them up.  As part of that blowing with the leaf blower (don't worry...I use an electric one from eGo and it isn't loud), I was cleaning up our firepit area.  And, for *some* reason, I looked closely at the stepping stones that take you from our lawn to the gravel bed.  One one of them - clear as day - was what sure looked like a fossil to my naked eye.  I got down on my knees and looked closer.  Sure enough.  I was certain we had SOMETHING.  That something...is what you see in the photo at the top of this post.    

If you look at the photo, the most striking detail is the spine-like ribs on the bottom/right of the flagstone rock.  But, right above it are some other things that made me think fossil. Here, below, is a closer look at those areas:

Those are fossils, right?  Here's the fossil imprints next to a USD quarter for size:

A quick tour on the Google Machine tells me that these are most likely Trilobites.  They're pretty common in Illinois.  From the Illinois State Geological Survey, I've discovered that these things *could* be hundreds of millions of years old.  H U N D R E D S of M I L L I O N S of years.  My brain can't quite comprehend that.

Trilobites were among the earliest inhabitants of Illinois. The oldest specimens have been found in Cambrian age rocks formed approximately 500 million years ago

The Paleozoic rocks of Illinois have long been known for their abundant and well-preserved trilobite fossils. Cambrian age trilobites have been found in a few small outcrops in north-central Illinois and in several cores drilled from deeply buried rocks at various localities throughout the state.

I don't know much about them - nor fossils in general - so I went to the Web to try to see if someone will help me identify them.  I found a couple of places (Carnegie Museum of Natural History,  Florida Museum) and have submitted these photos to see if they'll let me know what we have in our backyard.   Once they (if they?) let us know what we're dealing with, we'll figure out what to do with it.  Right now, I've left it in place - in our landscape.  But, I'm sensing a kid's school project on fossils coming in the next few years.  With an example from our *own* backyard as evidence.  That's kinda neat, right?