Lonesome George was believed to be the last remaining member of the tortoise subspecies, Pinta Island tortoise, and as his named implied he spent the majority of his life alone in his enclosure at Galapagos National Park in Ecuador. On Sunday however his keeper of 40 years Fausto Llerena found him dead, making the Pinta Islan subspecies effectively extinct.
He was estimated to be some 100 years old; he died young, considering most tortoise can live up to 200 years. On Twitter, news of his death didn't peak until Monday, when people began to mourn the loss of the gentle creature and the subspecies he represented.
His claim to fame included being named the loneliest creature on the planet by the Guinness Book of World Records. He was first discovered in 1972, and attempts to breed him with other tortoises failed after it was discovered that the eggs were infertile.
Here's a collection of the tweets mourning the death of Lonesome George.