What animal has a great memory?

Dolphins Have Longest Memories in Animal Kingdom

Marine mammals can remember their friends after 20 years apart, a study says.

New experiments show that bottlenose dolphins can remember whistles of other dolphins they'd lived with after 20 years of separation.

Elephants and chimpanzees are also highly intelligent and social beings.

Reference: Dolphins Have Longest Memories in Animal Kingdom (nationalgeographic.com)