horse mussel

noun4

1. •
   A northern horse mussel, any member of the species Modiolus modiolus of mussels of northern waters of Europe and the Atlantic and Pacific coasts of North America
2. •
   Any in subfamily Modiolinae of mussels.
3. •
   Atrina squamifera, of South Africa
4. •
   (New-Zealand) Atrina zelandica, a large bivalve common from low tide to 45 m depth with a thin, dark, wedge-shaped shell covered with hollow spines.