While diving in Monterey, I came across a harbor seal who had found a float on a string, anchored so the float was about 3 feet off the bottom. (It looked like it was part of some experimental aparatus.)

She was batting it around, clearly playing with it.

(Unlike other seals we ran into that day, she was uninterested in people. She reacted to us when we swam up but soon went back to playing with her toy and ignored us.)

Animals play.