| Pterotocrinus rugosus Mississippian Indian Springs Shale Sulphur, Indiana Size: 2 cm across the calyx. This is a plate from the famous Sulphur road cut. There is a small Phacelocrinus just below the Pterotocrinus calyx. | 
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| Pterotocrinus rugosus Mississippian Indian Springs Shale Sulphur, Indiana Size: 2 cm across the calyx. This is a plate from the famous Sulphur road cut. There is a small Phacelocrinus just below the Pterotocrinus calyx. |
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