acorn worm

or a·corn·worm

noun
  1. any of several burrowing, often brilliantly colored hemichordates of the class Enteropneusta, usually found in intertidal sand and mud, having an acorn-shaped proboscis and collar.

Origin of acorn worm

First recorded in 1885–90
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British Dictionary definitions for acorn worm

acorn worm

noun
  1. any of various small burrowing marine animals of the genus Balanoglossus and related genera, having an elongated wormlike body with an acorn-shaped eversible proboscis at the head end: subphylum Hemichordata (hemichordates)
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