Crinoidea
The crinoids were almost wiped out by the extinction event at the end of the Palaeozoic era. Four whole classes became extinct, and the few that survived became the only living class, the Articulata. The stalked members of the class sufered from heavy predation in the Mesozoic. and now all the remaining sea lilies are in deep water, where the competition is less fierce. The feather stars have been much more successful.