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Any of several small, wormlike marine animals of the phylum Phoronida that have a U-shaped digestive tract and inhabit self-made chitinous tubes.
[From New Latin Phorōnida, phylum name, from Phorōnis, type genus, probably from Latin, Phoronean, Argive (name of Io, priestess of Argos), from Phorōneus, son of Inachus, king of Argos, from Greek.]
(Animals) a small, wormlike marine animal which usually lives in the mud of the sea bottom and is hermaphrodite. Also commonly called: horseshoe worm