A needle in a haystack

General Something that is very difficult to find, especially because the area to be searched is too large.

Origin
It originated in the early 1500s, but using "meadow" instead of "haystack".

Vocabulary
This figure of speech exists in many other languages as well:

• Spanish: "una aguja en un pajar"
• French: "une aiguille dans une botte de foin"
• Italian: "un ago in un pagliaio"
• German: "Nadel im Heuhaufen"

Use
"Finding the right nail in his workshop is like trying to find a needle in a haystack."