A burrowing wormlike marine animal of shallow waters. Its body consists of a proboscis, a collar, and a long trunk with gill slits, and contains a structure resembling a notochord.
Class Enteropneusta, phylum Hemichordata‘The cilia on the larvae of acorn worms capture algae.’
- ‘Pterobranchs as very different from acorn worms; they form colonies in which the individuals are interconnected by stems, or stolons.’
- ‘An acorn worm isn't much more than a thin, cylindrical bag with a head and collar resembling an acorn.’
- ‘These coils often seen on the sand have been processed by the acorn worm.’