The Cheyenne Mountain Zoo said goodbye to beloved and well-known female giraffe Msichana this week, according to a release from the zoo.

Due to a recent decline in her health, caretakers made the “difficult, but compassionate” decision to humanely euthanize her. Her death follows months of successful treatment for age-related issues, zoo officials said.

The nearly 21-year-old reticulated giraffe was born at the zoo in 2002 and was the herd’s “welcome committee” for new members.

“Mishy Girl” was well-known for her tongue-out appearance as well as her role as a companion to newborn calves and new giraffe to the herd. In 2013, she had her own male calf named Kipawa, the release said.

According to the zoo, Msichana was confident, calm, nurturing, sweet, gentle and assertive. New giraffe found comfort in her presence and would learn from her by following her guidance.

“We could always count on Msichana to act as a ‘nanny,’ showing calves that other giraffe are friends, and helping new moms feel comfortable with their calves meeting other giraffe,” said Savannah Woods, animal keeper in African Rift Valley.

A strong and social ambassador with guests at the zoo, she helped hundreds of thousands of people connect with her species, the zoo said. She also taught her care team valuable lessons that help shaped the zoo’s giraffe training program.

“I would call it a once-in-a-lifetime relationship, and she was a once-in-a-lifetime giraffe,” said Woods.

Msichana would have turned 21-years-old on Sept. 21.

The median life expectancy for giraffe in human care is about 16 years, according to the Association of Zoos and Aquariums.