The Australia Zoo celebrated a 175th birthday for Harriet, a Galapagos tortoise (Geochelone nigra) who is estimated to have been born around 1830. Harriet has lived at the Australia Zoo for 17 years and, according to the Australia Zoo website, is thought to have been collected by Sir Charles Darwin in 1835. Harriet is also thought to be the world's oldest living animal.

Find out more: 175th Birthday Bash for Tortoise (BBC News)