Indonesian Mimic Octopus

"This fascinating creature was discovered in 1998 off the coast of Sulawesi in Indonesia, the mimic octopus is the first known species to take on the characteristics of multiple species. This octopus is able to copy the physical likeness and movement of more than fifteen different species, including sea snakes, lionfish, flatfish, brittle stars, giant crabs, sea shells, stingrays, jellyfish, sea anemones, and mantis shrimp. This animal is so intelligent that it is able to discern which dangerous sea creature to impersonate that will present the greatest threat to its current possible predator."

(more at Wiki)