This is called the Coffer illusion. There are 16 circles in this image.

Very visual example of ground current from a lightning strike. Lightning struck the green of the 15th hole at The Champions Course at Weeks Park in Wichita Falls, TX, last year. Lightning spreads out along the ground in something called "ground current."

Backyard Bees of North America. This poster is 24" x 36" and details 130 bee species (enlarged 5x). beesinyourbackyard.blogspot.com/p/poster.html 'The Bees In Your Backyard. A Field Guide to the Bees of North America' (2015) Princeton University Press.

Ring lightning