Biologist your help needed about illusions?

Question

Please biologist I need your help to explain the illusion in my own words from this site . www.michaelbach.de/ot/

See the illusion from the site above and say if you saw the illusion if you didn't just say no. Explain the illusion please in short detail. Thanks

For example: “Stepping feet” Motion Illusion. Do you see illusion here ? and explain what do you see?

Answer 1

There are 78 illusions on that site!

You will have to give a more specific link than that...