Here is another extremely rare crinoid from the Waldron Shale Formation of Indiana. This crinoid, Periechocrinus whitfieldi, is beautifully preserved on a large matrix piece that contains a Platyostoma plebium gastropod feeding off the anal opening of the Periechocrinus crinoid. The crinoid cup measures 2 1/2" long, the gastropod measures 1 3/4" wide, and the stem that is attached to the cup measures 4 1/2" long. The Periechocrinus cup has been cleaned so both sides can be seen with the gastropod attached to the anal opening. This is truly on the most interesting crinoid/gastropod associations I have ever seen from the Waldron Shale.

Periechocrinus Crinoids