Echiuroidea
Echiuroidea , noun, plural
[New Latin, from echiurus, the name of one genus (Greek 'e`chis an adder + o'yra` tail) + -oid.]
(Zoology) A division of Annelida which includes the genus Echiurus and allies. They are often classed among the Gephyrea, and called the armed Gephyreans.