In folk culture, Turtle is one of the Four Sacred Animals, a symbol of longevity. The image of Turtle is associated with the heroic history of the Vietnamese nation through the legend of the Golden Turtle who lent his claws to An Duong Vuong to make a magic crossbow to defeat the Trieu Da army in the 3rd century BC. According to the legend, in the 15th century, thanks to the golden turtle lent the magic sword to King Le Loi so he won the resistance war against the Ming invaders and gained independence. After ascending the throne, King Le Loi returned the magic sword to the golden turtle on Luc Thuy Lake (Hoan Kiem Lake or Lake of the Restored Sword now), and the turtle living here is called Sword Lake turtle to associate with this event.

Sword Lake turtle, scientifically known as Rafestus swinhoei, is a rare species of turtle, with only 06 left in the world. Currently, at Ngoc Son temple, two specimens of Sword Lake turtle are displayed, which Vietnamese people often call “old turtle”.

The first specimen displayed in the outer glass cabinet (near the door) is the “old turtle” died in 1967. At that time, the turtle’s weight was 250kg, the shell was 2.1m long and 1.2m wide, preserved by the method of stuffing and impregnating with chemicals. The second specimen (in the inner cabinet), died on January 19th, 2016, weighing 169kg, the shell was 1.85m long and 1.08m wide, preserved by plasticization technology of the Federal Republic of Germany. The process of making and preserving the specimen has taken place since 2016, and completed in 2018; including the use of advanced materials to preserve the specimen for a long time, while keeping the natural size as well as the bones inside the body, ensuring that the specimen is close to the image of “old turtle” when it was alive.

The Sword Lake turtle specimens are displayed at the temple located on Ngoc Island associated with the legend of King Le Loi’s return of the sword. The storage cabinets are specially designed, including super white double-glazed reflective glass, cold laser light system and modern dehumidification and air filtration system. These rare and precious specimens will be preserved for a long time, promoting the unique specific, historical and cultural values of Hanoi in particular and Vietnam in general, meeting the aspiration of visitors, scientists and researchers when coming to Hanoi and Vietnam.