This picture is a flat representation of a 3D figure so it doesn't have to follow the 3D rules so you can draw it how ever you want. They didn't actually draw the legs, they just drew spaces and your brain is trying to process that and it makes it look like legs. B.T.
DiSpezio, Michael A. Optical Illusion Magic: Visual Tricks & Amusements. New York: Sterling Pub., 1999. Print.
"Elephant Legs Optical Illusion." Mighty Optical Illusions RSS. N.p., 06 Dec. 2013. Web. 17 Mar. 2015.