Famous cat Lil Bub has died at the age of 8.
On Monday, the feline’s owner, Mike Bridavsky, posted on social media that his beloved friend had passed on Sunday.
“We lost the purest, kindest and most magical living force on our planet. BUB was cheerful and full of love laying in our bed with us Saturday night, but unexpectedly passed away peacefully in her sleep,” wrote Bridavsky in Lil Bub’s weekly newsletter.
Bridavsky explained that he’s been “fully transparent” about Lil Bub’s poor health and that it “was no secret that she was battling a persistent and aggressive bone infection.”
Despite that, he says he wasn’t “expecting her to pass so soon or so abruptly without warning.”
“I truly believe that she willingly made the decision to leave her failing body so that our family would not have to make that difficult decision ourselves,” he said in the newsletter.
Lil Bub became a viral celebrity in 2011 when her photos took off after being posted on Tumblr and then later on Reddit. Born with several genetic mutations, the animal had an extreme form of feline dwarfism that led to her tongue always hanging out because of a shorter lower jaw and toothlessness; she also suffered from osteopetrosis, a bone disease that makes bones abnormally dense and prone to breakage.
After achieving internet stardom, the feline went on to helm the documentary “Lil Bub & Friendz,” which won the Tribeca Online Festival Best Feature Film. She was also the focus of the book “Lil Bub’s Lil Book: The Extraordinary Life of the Most Amazing Cat on the Planet,” which came out in 2013.
Bridavsky highlighted more of Bub’s achievements in his note about her death: “She has literally saved thousands of lives (both pets and humans), she started the first national fund for special needs pets, she was the subject of groundbreaking genetic and biological research, she’s helped raise over $700,000 for animals in need, and has spread a message of determination, positivity, and perseverance to people all over the world,” he wrote.
“And even though my heart is absolutely crushed by her graceful departure from planet Earth, I know that her sprit, magic, and overwhelming energy are still with us, reminding us every day to be better.”
Many on social media mourned the passing of the furry friend:
This article originally appeared on HuffPost.