A stereogram is a 3D picture within a picture. Hidden inside each image is an object which appears in 3D when viewed correctly.
Brontosaurus
Cube
Hand
Donkey
Guitar
Dolphins
Tea Pot
Sports Car
Ant
Horse
Jeep
Heart
Boat
Skull
Skateboard
Strawberry Man
Motorcycle
Helicopter
Globe
Flying Bird
Box
Face
Dog
Dinosaur
Cow
Cauldron
Fish