Elephants return to touch the bones of their dead, sometimes years later

Elephants that come across a dead herd member, or even just its bones, often stop to investigate — touching and lifting the remains with their trunks, standing around the body for extended periods, and sometimes covering it with branches and soil. They've been seen revisiting relatives' bones long after death, and seem able to tell elephant remains from other animals' by smell and touch alone. Researchers still debate how much of this reflects grief as humans understand it versus curiosity.

— Wikipedia contributors, Elephant Cognition — Behavioral ecology