1.35" Macrocrinus Crinoid Calynx With Anal Tube - Indiana

This is a 1.35" calynx of Macrocrinus mundulus crinoid with preserved anal tube, collected near Crawfordsville, Indiana. It's been cleaned under microscope using air abrasives.

It is believed that crinoids from the Ramp Creek Limestone were buried in sediment from nearby deltas during storms. The resulting siltstone deposits are soft enough that fossils can be extracted in exquisite, three-dimensional relief.