The mammal known to have the most extended memory is the elephant. Elephants possess remarkable cognitive abilities and demonstrate an impressive capacity for memory. They are known to remember locations of waterholes, social relationships, and even human faces over many years. Their long-term memory is believed to be a vital survival trait, enabling them to navigate vast landscapes and adapt to their environment. Additionally, elephants can recall social bonds with other elephants even after years of separation. This impressive memory allows them to form strong family ties and navigate complex social networks, making them one of the most intelligent animals in the animal kingdom.