Stephanocrinus gemmiformis   scale in cms CLASS - Coronoidea ORDER - FAMILY - GENUS/SPECIES - Stephanocrinus gemmiformis ROCK UNIT - Rochester Shale AGE - Middle Silurian (425 million years old) LOCALITY - Niagara Gorge, near Lewiston, New York, USA Although once considered a blastoid, Stephanocrinus lacks the food grooves and central mouth that blastoids have. These fundamental differences are enough to justify a new class of echinoderm (Coronoidea), of which Stephanocrinus is the only known example. Although it is unusual, it is by no means rare in New York. In fact, it is one of the most commonly occurring echinoderm fossils in the Rochester Shale. PRI 42977