The Japanese giant spider crab (Macrocheira kaempferi) is the largest arthropod known today. Adult specimens can be nearly 4 meters long from claw to claw, its forelegs reach up to 1.5 m, and can weigh up to 20 kg. It is very long-lived, some specimens are known to be about 100 years. The arrival of the specimen at the MNCN is not dated, but by the type of glass box containing it, with a crystal similar to that manufactured in the Real Fábrica de Cristales de La Granja, one could say that it comes from the second quarter of the 19th century.