Gennaeocrinus variabilis   scale in cms CLASS - Crinoidea ORDER - Monobathrida FAMILY - Periechocrinidae GENUS/SPECIES - Gennaeocrinus variabilis ROCK UNIT - Bell Shale AGE - Middle Devonian (385 million years old) LOCALITY - Rockport Quarry, Alpena, Michigan, USA Gennaeocrinus like many other Paleozoic crinoids (of the Subclass Camerata) has a calyx (main body portion) which is strongly sutured together, so it rarely breaks apart after death. These display a canopy of small plates (called a "tegmen") that cover the mouth on the upper surface of the calyx . Plates around the anal opening (located near the center of the tegmen) usually form a knob or tower (seen from top view - in lower right specimen). The lower portion of the arms were incorporated into the calyx and form a regular series of projections along the outer edge (easily seen in bottom and top views - lower left and right, respectively). PRI 43959