You can grow "animal plants" -- commonly called Topiary -- that look like they're formed entirely out of plant material using "wire art" kits from Green Piece Wire Art.
The company sells detailed animal sculptures made of closely spaced wire that's filled with rich green sphagnum moss. The idea is to grow the moss inside a wire frame shaped like an animal or other object. The sculpture can then be seeded with plants that replicate animal features i.e. grass for a horse's mane and tail or small flowers across a turtle's back.
More than 70 "wire art" characters are available. The wire is epoxy powder coated to prevent rust. To add accent plants, you simply poke holes into the moss and then plug the plants into the holes. The company makes suggestions on which plants to use. It has also compiled a list of growers who carry topiary friendly plants.
"Wire art" characters available include everything from frogs, turtles, cats and dogs, to dinosaurs, alligators, elephants and giraffes.