Isocrinida

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Isocrinida (sea lilies; class Crinoidea, subclass Articulata) An order of sea lilies which have a long stem, characteristically five-lobed in cross-section, which bears whorls of cirri at irregular intervals along its length. The small calyx is dicyclic, with concealed infrabasals. The arms are generally branched several times. The order is known from the Triassic to the present.