Emmanuelle,
Where are you from ? Your name sounds French and obviously you read French. You are totally right. Unfortunately, this (not very serious indeed) translation is very funny and more than confusing but it is a very old translation from an external - and obviously not so serious - source. I will correct it right away. As you seem to know, "noix" in French is walnut and we use it also for things that have a walnut shape, like the muscle of the scallop. But the translation could have been worse !...
If you look at more recent translations, I do hope you will find some improvement.
All the best