What is "crustulum"?
Maybe this is a silly question but I'd still like confirmation.
When I first encountered this word on the course I thought nothing of it. But I recently read a post asking for clarification on what the word meant. Both the language used in the question and the language used in the best answer clearly indicate that the definitions those people were using were not anything like what I'm accustomed to. In addition, I saw all kinds of explanations in other answers.
I think it would be clearer if I got an answer about pictures instead. So, which, if any, of the following images would a Roman actually consider "crustulum"?
For reference, I consider (1) and (4) to be cookies, (2) a biscuit, and (3) a cracker.
Is this the discussion you meant?
Crustulum is a diminutive used for some sort of baked good. Of which a biscuit or cookie or cracker might be an example. Track down the references given in the dictionary article referred to, read them, and see what you think.
No photographs survive from ancient Rome. Unless there are preserved pictures of a bake shop, which there may be, or cookbook descriptions, or crustula preserved in Pompeii or Herculaneum, probably all we can do is take our best guess or borrow the word to describe modern varieties of small baked goods.
Search online for "crustulum" and you will find some discussion.