Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or … 展开

The basic body form of a crinoid is a stem (not present in adult feather stars) and a crown consisting of a cup-like central body known as the theca, and a set of five rays or arms, usually branched … 展开

Origins
If one ignores the enigmatic Echmatocrinus of the Burgess Shale, the earliest known … 展开

Fossilised crinoid columnal segments extracted from limestone quarried on Lindisfarne, or found washed up along the foreshore, were threaded into necklaces or rosaries, … 展开

The name "Crinoidea" comes from the Ancient Greek word κρίνον (krínon), "a lily", with the suffix –oid meaning "like". 展开

Most modern crinoids, i.e., the feather stars, are free-moving and lack a stem as adults. Examples of fossil crinoids that have been interpreted as free-swimming include Marsupites, … 展开

Crinoidea has been accepted as a distinct clade of echinoderms since the definition of the group by Miller in 1821. It includes many extinct orders as well as four closely related living orders (Comatulida, Cyrtocrinida, Hyocrinida, and Isocrinida), which are part of the … 展开