An 18-year matriarch passed away at the Sacramento Zoo Friday morning.

Ravenala, the zoo’s black and white ruffed lemur, was found deceased inside her pen during Friday morning during morning rounds, zoo officials said.

“She was nothing short of amazing and has left a lasting legacy for her critically endangered species as well as an indelible print on all of our hearts,” zoo staff said.

There doesn’t appear to be any immediate known cause of death, staff said, but Ravenala appears to have passed away in her sleep.

Staff said the death was unexpected as the lemur had no shown any unusual signs over the prior week. At 18, Ravenala was an older lemur, though, with the species typical life expectancy being about 18-and-a-half years.

“Ravenala was nothing short of amazing. I had the privilege of watching her grow her family for 13 years, said Lead Primate Zookeeper Janine Steele. “She was a gentle and patient mother while being a fierce protector of her family and territory.”

“She most definitely had people she tolerated and strong feelings towards people she didn’t care for. I feel honored and grateful to have been one of the lucky ones she tolerated. Ravenala was one of those extra special individuals that will stay with me forever.”

Staff called Ravenala a “strong matriarch and much-loved resident of the Sacramento Zoo who has left a long-lasting legacy that spans the zoos across the country.”

The lemur moved to the Sacramento Zoo in 2004 from the St. Louis Zoo. She and her mate, Jacque, had six litters totaling 18 offspring, eight of which currently reside at the Sacramento Zoo.

Ravenala had a lot of spunk and was a force to be reckoned with as females are indeed the backbone of lemur societies, staff said.

“Ravenala endeared herself to many by demanded nothing short of the best,” staff wrote. “Her passing is a great loss that is felt deeply by zoo staff.”

During the coming days and weeks, zoo staff and veterinarians will be closely monitoring the family group. Ruffed lemurs are female dominant and the loss of the female family leader will cause a shift in the group social dynamics.

Black and white ruffed lemurs, a Critically Endangered species, according to zoo staff, and are native only to the island of Madagascar off the southeastern coast of Africa.