The Almeida family lost their tortoise Manuela in 1982 after having building work done on their house, and after a lot of searching never found their pet.
However, after their father died earlier this month the family began clearing out the room which he had used to store broken electrical items.
The family, from Rio de Janeiro, were shocked to find the tortoise alive inside a box containing an old record player.
Son Leandro told Brazil's Globo G1 website: "I looked and saw her. At that moment, I turned white, I just couldn't believe what I was seeing."
Vet Jeferson Piers explained that some species of tortoise can survive up to three years without food and are extremely resilient. He suspects Manuela may have survived by eating termites from the wooden floor.