I saw this sentence and was wondering the same thing. After being told time and time again that I was "overusing -miş" I all but dropped it from my active vocabulary.
What difference is conveyed here through using "yapılmış" instead of "yapıldı"?
because you did not see that it was being made :) And this is also sort of a fixed usage, for "made of" always use "yapılmış".
Which/What material was this spoon made from
Correct English (i.e. not ending with a preposition..) "From what material is this spoon made?"
Why is -miş being used here?
If you ask someone who made the spoon or saw the process of making you can use "-dı", but if you ask someone who didn't made the spoon but learned from someone else how spoon made then use "-miş".