Recently, while I was doing field work volunteering for the Denver Botanic Gardens in Hoosier Pass, I took time over lunch to look for any potential fossils. What had found was very strange, they looked to be fossils of Essexella and Reticulomedusa as found in Mazon Creek nodules. I believe that the history would make sense for them to be able to be found in Colorado, but I do not know.
Here are my photos, with a penny for scale.
EDIT: I will reply with more photos due to the max filesize
the one here appears to me to be Reticulomedusa, but I need an expert opinion to confirm or deny.
I believe that the reason that they aren't in well-defined exposed nodules like in Mazon Creek is due to the fact that they would open annually due to the freeze-thaw process happening naturally, without having the rest of the surrounding rock mined away.