acorn worm

American  

Or acornworm

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.

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acorn worm British  

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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Etymology

Origin of acorn worm

First recorded in 1885–90

Example Sentences

The researchers found that the genes in the head region of the acorn worm were “switched on” in the starfish’s bumpy skin, which covered its entire body.

From Scientific American • Nov. 3, 2023

A rather uncommon marine worm, called Balanoglossus or the acorn worm, has a very strong and unpleasant smell like that of iodoform.

From More Science From an Easy Chair by Lankester, E. Ray (Edwin Ray), Sir