Flexibilia
The Flexibles belong to the so called
"Cladids", originating during the Ordivician and along with most
other crinoids did not survive the
Permo-Triassic extinction.
Morphologically the
Flexibles have a conical
dicyclic cup
with loosely articulating
plates; uniserial arm with no pinnules; a flexible
tegmen
with many small plates;
and a circular stem with no cirri.