Definition of sea mouse in US English:

sea mouse

noun

  • A large marine bristle worm with a stout oval body that bears matted iridescent chaetae.

    Genus Aphrodite, class Polychaeta

    • ‘Various species of polychaete are known as lugworms, clam worms, bristleworms, and sea mice.’
    • ‘Some polychaetes such as the sea mouse also bear a ventral muscular, creeping sole.’
    • ‘We have found another stray from the deep, a creature we had been curious to see for years - the ratfish, or sea mouse.’