I was looking for an octopus (it’s a long story) when I stumbled upon the complete plates of Ernst Haeckel’s 1904 Kunstformen der Natur. They’re beautiful.

(The octopus I was looking for is featured in the BibliOdyssey book, and turns out not to be by Haeckel at all. It’s here, along with an enormous number of other plates — there’s more Haeckel too.)