fit = ?

The phrase you need to investigate is: fit a new piece into the puzzle.

The 'puzzle' is the question of how some bees become queens. Puzzles are made from pieces that fit into one another to reveal a complete picture.

Now researchers have found another clue to help find the answer to this question.

PS Study idioms, similes and metaphors to better understand English.

This is a very good piece of advice.

In British English the sentence quoted contains an error. In American English it does not.

In British English, the past participle of "fit" is "fitted", so that the sentence in question would read "Now, researchers have fitted a new piece into the puzzle". However in American English, the situation appears to be more complicated. I believe Americans generally prefer the simple past and past participle form "fit". However, when the verb "to fit" is used to mean "to tailor," they seem to prefer "fitted".

By the way, we generally fit pieces into a special kind of puzzle, called a "jigsaw puzzle".

Thank you all