A group of mussels is commonly referred to as a "bed" or a "gathering." These bivalve mollusks often cluster together on submerged surfaces, forming dense colonies. The term "bed" typically describes their habitat rather than a social grouping like in some other animal species.
galaxy
A herd.
A group of nine is called an ennead.
The answer is: a pack ! Isn't that easy?
A group of galaxies is called a cluster.
a group of unicorns is called a unicircle or unicluster
A group of mussels collectively are called shellfish, clams, bivalves and unionids.
Sheep is always Sheep whether Plural or Singular
A forest, a grove, a wood, a copse, a stand of timber or even a jungle
a litter
The Chillaxes
yes