The Magnifying Lens can be found inside a cave to which the entrance is revealed by inserting the Scale into The Mourning Mermaid in Martha's Bay. The Magnifying Lens can be used to find things not normally visible to the human eye, making it similar in function to the Lens of Truth. Using it allows Link to encounter a Goriya with whom he can trade certain items for a Boomerang in Toronbo Shores. The Magnifying Lens also allows Link to read the book found in the Library in Mabe Village with the fine print that contains the answer to the puzzle in the Wind Fish's Egg. As such, it is almost required to complete the game; it is possible to skip the Magnifying Lens by testing all the possible paths through the egg.