Notocrinus virilis is a marine invertebrate, a species of crinoid or feather star in the family Notocrinidae.

[3] Like all crinoids, it is a filter feeder, spreading its arms and pinnules widely to catch plankton and small particles of detritus from the water flowing past.

More recently, it has been discovered that N. virilis often has a gastropod mollusc, Bathycrinicola tumidula, attached to it, the first time a snail from this family has been associated with a crinoid.

Research in 2007 by Schiaparelli showed that B. tumidula is parasitic on N. virilis, and no other Antarctic crinoids have been found to act as hosts to the mollusc.

Some of the parasitic snails were found to have inserted their proboscises between ossicles near the base of the crown while others were attached between calcareous plates on the arms.