Thailand's oldest hippopotamus "Mae Mali" eats fruit and vegetables during her 55th birthday party at Khao Kheow zoo in Chon Buri, Thailand September 8, 2020. As children and other spectators sang to mark her 55th birthday, Thailand's oldest hippopotamus Mae Mali chomped on an assortment of fruit and vegetables arranged in the shape of a cake. REUTERS/Soe Zeya Tun

Thailand's oldest hippopotamus "Mae Mali" eats fruit during her 55th birthday party at Khao Kheow zoo in Chon Buri, Thailand September 8, 2020. Mae Mali, which means "Mother Jasmine" in Thai, who moved to a compound at Khao Kheow Open Zoo in eastern Thailand two years ago from a zoo in Bangkok, and has already outlived a hippo's typical life expectancy of around 40 to 50 years old. REUTERS/Soe Zeya Tun

Thailand's oldest hippopotamus "Mae Mali" is seen during her 55th birthday at Khao Kheow zoo in Chon Buri, Thailand September 8, 2020. REUTERS/Soe Zeya Tun

A leech is pictured near the eye of Thailand's oldest hippopotamus "Mae Mali" during her 55th birthday at Khao Kheow zoo in Chon Buri, Thailand September 8, 2020. REUTERS/Soe Zeya Tun

Thailand's oldest hippopotamus "Mae Mali" is seen during her 55th birthday at Khao Kheow zoo in Chon Buri, Thailand September 8, 2020. REUTERS/Soe Zeya Tun