Crinoids, or Feather Stars, are not only spectacular by themselves, they also host spectacular commensal animals like small shrimps, cling gobies and tiny lobsters, most perfectly disguised within the Crinoid. I will post some pictures of those later.
As Echinoderms, they are family of Starfish and Urchins. However they have their mouth on the upside, unlike their family members.
Crinoids are suspension feeders. With tiny tube feet on their arms they catch plankton and detritus, to be directed trough a central channel towards the mouth.
Over 500 distinct species are described. The earliest traces of those animals go back almost 500 million years!