Over the weekend, a 19-year-old Malayan tapir died at the Woodland Park Zoo.

Known as Ray, the tapir had been living at the Woodland Park Zoo for 18 years, and weighed 725 pounds. Ray had been undergoing treatment for reduced appetite and inactivity.

The Zoo’s associate veterinarian, Doctor Kelly Helmick, had stabilized Ray’s condition, so the death was unexpected. A necropsy suggests organ failure; however, other tests will be conducted to determine final cause of death.

In the Zoo’s press release, mammal curator, Martin Ramirez, explained the loss.

“We are very saddened by this loss. Several staff members have cared for Ray since he arrived at the zoo more than 18 years ago, so it’s especially hard for them. …We will miss Ray, particularly splashing through his pool, a favorite activity of his.”

One of the most primitive large mammals in the world, the Malayan species is the only tapir native to Asian and is currently endangered. The average weight for an adult is 750 pounds, though some reach 900.

Plans for another tapir are not yet decided, yet one tapir remains at the zoo: a new two-year-old female, named Ulan.