Optical Illusions

A friend of mine let me borrow his phone for a day. I noticed some photos in his gallery. They are called optical illusions. I am really amazed with the photos he has.  I even asked him why he has these photos saved in his phone. He said that he is also having fun looking at those optical illusion photos. When we saw each other again, we even looked for more photos on the net. Do you know these optical illusions too? Then go look for them and have your mind blown by these, because my mind was blown too.