You searched for: “mussel
muscle, mussel, muzzle, muzzle
muscle (MUHS uhl) (noun)
Tissue in the body that contracts when stimulated thus causing movement: The muscle in Phil's leg was killing him because he had been running too fast and too long.
mussel (MUHS uhl) (noun)
A marine bivalve mollusk common to both the sea and fresh water: The interior of the shell of a mussel is pearly and smooth.
muzzle (MUZ uhl) (noun)
1. The forward, projecting part of the head of certain animals; such as, dogs, including the mouth, nose, and jaws; the snout: Helena pet the muzzle of the cute little puppy.
2. A leather or wire restraining appliance that, when fitted over an animal's snout, prevents biting and eating: The by-law in the city required that every dog wear a muzzle to prevent it from hurting people and other dogs.
3. The forward, discharging end of the barrel of a firearm: Martin pointed the muzzle of the gun at the target and pulled the trigger.
muzzel (MUHS uhl) (verb)
To keep individuals or groups from expressing their thoughts or opinions: The city bosses attempted to muzzle the press to prevent a corruption scandal.

Obviously we cannot muzzle a mussel in order to see its muscle.

A unit related to: “mussel
(Latin: Probably from mitulus "mussel", of unknown origin [the change from m to n has not been explained]. It is also said to possibly come from Latin nidificare or nidulari, "to nest"; from nidus "nest", but there is no confirmation for either theory)