The answer to the title of this post is only when you think it is. Curious people see life as a lesson to be learned. They view happenings as relative to one another, and they try to find similarities between things. The design of one thing can inspire the design of another. So what are the similarities between fish and currency? Take a look at the images below and makeup your own mind. The first is a 20 pesos banknote from Uraguay. The fish is a butterfly ray. Both are spectacularly designed. The link below the butterfly ray takes you to more amazing images of fish.