Facts, Memes, and Trash: uber
 facts
 At the Institute for Marine Mammal Studies in
 Mississippi, dolphins Were trained to turn in
 trash that fell into pools in exchange for fish.
 One dolphin was smart enough to hide pieces of
 paper under a rock, and tear off smaller pieces
 from that paper in order to get more fish.
 UberFacts 2015
Genius dolphin. 

http://www.theguardian.com/science/2003/jul/03/research.science