mussel

Take a quick gander at your muscles. Do you think they look anything like … mice? And do you think mice resemble  mussels, as in the edible mollusk? This may sound odd to you, but to the ancient Romans, it would have made perfect sense.

This is because both the words muscle and mussel come from musculus, which literally means “little mouse” (mus means and is related to “mouse”).

As far as we can tell, the ancient Romans thought that the movement of a muscle, especially when flexing, looked like a mouse was running under your skin. If you don’t know how muscles work, it sounds as reasonable a guess as any.

Now to the mollusk: the ancient Romans apparently also thought that mussels, the shellfish, looked like little mice. The word mussels also comes from that same Latin noun as muscle: musculus.

The roots of these other words may get a rise—of laughter or surprise—out of you. Run on over to our roundup of them at “Weird Word Origins That Will Make Your Family Laugh.”

To recap, a mussel is a kind of shellfish and a muscle is a part of the body—neither one are mice. Mussel is a collective name for more than 1,000 species of this type of mollusk. Some species of mussels are eaten as food. This is also the case for other animals that mussels can easily be confused with: clams, oysters, and scallops.

Besides their use as food, mussels are also sought after by humans because, like oysters, they create pearls. But zebra mussels are an invasive species that can harm other animals and clog water mains, resulting in millions of dollars being spent to remove them.