Lonesome George, a giant tortoise thought to be the rarest creature in the world, has died at the Galapagos National Park in Ecuador. He was about 100 years old. 

It is widely believed that the Pinta Island tortoise was the last of its subspecies. For decades, environmentalists had tried to get Lonesome George to reproduce with females -- but they were unsuccessful, according to the BBC. 

A post-mortem will be conducted on the tortoise to determine the cause of his death. 

5 Things to Know About the Rare Creature:

  • George was first spotted on the island of Pinta on Dec. 1, 1971 by Hungarian malacologist Jozef Vagvolgyi. 
  • The Pinta giant tortoise is an extinct subspecies of the Galapagos tortoise native to Ecuador. Tortoises were plentiful in Galapagos until the late 19th century, but they were later hunted down by sailors for their meat, which paved their way to extinction, according to BBC News. Some 20,000 giant tortoises of other subspecies still live on the Galapagos.
  • Lonesome George served as a potent symbol for conservation efforts in the Galapagos and internationally. 
  • After a series of unsuccessful mating attempts, the Darwin Station offered a $10,000 reward for a suitable mate for George. 
  • In 2009, George had successfully mated with one of his female companions. The eggs were moved into an incubator, but once the incubation period had ended, it was announced that they were unviable. 

Meeting Lonesome George

Melanie Stetson Freeman, a staff photographer for the Christian Science Monitor, met Lonesome George while on assignment in Galapagos in 2009. 

The first time I went there, you weren't allowed to see Lonesome George, because he was so unusual, they were really taking care to protect him, she recounts for the Monitor.

When she returned to the Islands, she managed to secure full access and spent hours with the rare tortoise. 

I would go back whenever there was empty time, go back and just sit there and watch, she said. Not like he moved around so much, but just watching the slow crawl of an ancient creature, one of the world's rarest, his wrinkly skin, and really long neck; I thought he was adorable.