Brian, 

‘ Noix de Saint-Jacques ‘ refers specifically to the scallop (meat). ‘Noix’’ is used in many contexts other than just for walnuts/nuts. It is unlikely that a question would be asked about ‘undercooked walnuts/nuts’.

Something made with nuts as a complementary component would be ‘…  aux noix ‘. Think of ‘champignons or poulet à la crème’ etc

https://www.wordreference.com/fren/noix

Hi Maarten, thanks, this makes perfect sense of the sentence in the exercise “Patrick a remarqué juste à temps que les noix étaient encore translucides !”. The translucent “noix” must be an abbreviation for “noix de Saint-Jacques”, i.e. scallops that were translucent due to them being under-cooked!

Hi Cécile, no problem. 

Here we call the edible part “scallop”, but we call the creature itself that too. Probably similar to how “crab” might refer to crab meat (“I’m eating crab”), or to a whole animal (“I saw a crab”). 

I didn’t know about “mie de pain” - interesting! I don’t think we have an equivalent, although kids often ask with reference to their sandwiches “can you cut the crusts off please?”

Cécile, just to confuse everyone, the equivalent of ‘mie de pain’ in English is actually technically ‘crumb’. That is, bread has the exterior crust and the interior crumb. The crumb of the bread is not quite the same as ‘breadcrumbs’ !