What is "crotalocrinites"

Crotalocrinites, also known as the feather star, is a genus of extinct sea lily belonging to the family Crotalocrinitidae. These feather stars were stationary intermediate-level organisms feeding on suspension epifauna. They lived in the Silurian period, from the Upper Wenlock age (428.2 ± 1.5 to 422.9 ± 2.8 mya) to the Ludlow age (422.9 ± 1.5 to 418.7 ± 2.8 mya).