Algal designs for money!

Happy Birthday to M. C. Escher. Everybody TPP knew in college had an Escher print, or two, hanging in their rooms; they were so clever, so well designed, so much fun, but who knew he tried designing money?  The designs on this bank note are algae: a diatom, Pediastrum, Spirogyra, a volvocalean colony, and more. This is the real green stuff, of course, it's only in the USA where all the bank notes are the same boring algal-colored green.