Elephants never forget a face, not even their own
Elephants have now been granted access to the inner sanctum of animal intelligence as evidence mounts that they can recognise themselves in the mirror.
Three Asian Elephants, known as Happy, Maxine and Patty immidiately recognised the mirror as an illusory device, and not a threatening unknown animal (typical response of a cat or other non-self recognising animal). The final test off Mirror Self Recognition involves self-directed behaviour. This is using the mirror to examine oneself, and showing that vanity is an intelligence related factor, this is tested by placing a mark or blemish on the creature and seeing if it notices. Happy was given a white cross above her eye (apparently without her noticing) and when she saw it in the mirror, she began to probe about on herself, not the reflection.
The BBC has a fact sheet on other aspects of elephant intelligence.
Other animals with shown Mirror Self Recognition are humans over 2, orang-utans, chimpanzees, and maybe dolphins. Other candidates for testing include killer whales.