I finally got my own copy of the classic Art Forms in Nature (Kunstformen der Natur) by Ernst Haeckel. Yes, the prints are all online, but that isn’t quite the same thing. This collection of 100 prints, first published as a set in 1904, is a true classic.
Is it an art book or a science book? It doesn’t really matter, does it? It’s beautiful, and it’s informative. Everyone should cast their eyes over these pictures at some point. These images influenced the Art Nouveau movement, and have also found their way into many books on the relationship between mathematics and science. And they are just fun to peruse.