Staff and visitors in Arizona are mourning the loss of one of the most popular animals at a Phoenix zoo after an African Lion named Boboo was euthanized according to officials on Saturday, The 8-year-old lion was diagnosed with an aggressive form of cancer. Zoo officials said the cancer was so aggressive that just last month Boboo showed no signs of illness during an annual exam.Boboo first came to the Phoenix Zoo in 2019 from the Columbus Zoo. Another lion, Zuri, had just given birth to Boboo's first litter of cubs. Zoo officials say the mom and two cubs are "doing very well and exceeding expectations with their growth."This story was originally published by Scripps News Phoenix.