What kind of burrows are these?

[SilurianSalamander]

I found these burrows in Ordovician-Silurian rocks in Waukesha Wisconsin. I found hundreds of these just a few weeks ago in Green Bay WI (Ordovician) any way to identify what animal made these burrows? Thanks!

 

ps: so sorry I forgot the scale

[Tales From the Shale]

If I had to hazard a guess, I'd say they're worm burrows. As those are by far the most common ichno burrow found within old Paleozoic rock. I'm guessing since it's near Waukesha it's Silurian?

[Rockwood]

I wouldn't rule it out, but honestly I'm not sure these are burrows. Ichno fossils are rarely associated with a specific animal. Many body shapes are capable of making what might appear to look like a worm hole.